[Federal Register Volume 91, Number 95 (Monday, May 18, 2026)]
[Proposed Rules]
[Pages 28463-28487]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2026-09905]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 85, 86, and 1066
[EPA-HQ-OAR-2025-3297; FRL-13030-01-OAR]
RIN 2060-AW96
Revision of Tier 4 Criteria Pollutant Standards, Part 1:
Amendments to Phase-In Schedule for Light-Duty and Medium-Duty Vehicles
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
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SUMMARY: The U.S. Environmental Protection Agency (EPA) is
reconsidering the Tier 4 criteria pollutant standards for new motor
vehicles promulgated within the final rule entitled ``Multi-Pollutant
Emissions Standards for Model Years 2027 and Later Light-Duty and
Medium-Duty Vehicles.'' This reconsideration will occur in two
separate, but coordinated, rulemakings. In this Part 1 rulemaking, the
EPA is proposing to amend the phase-in schedule for the Tier 4 criteria
pollutant standards for certain vehicles to address changing
circumstances and feasibility concerns. These amendments, if finalized,
would extend the Tier 3 standards for certain vehicles to model years
(MYs) 2027 and 2028 such that the Tier 4 standards for these vehicles
would phase in starting with MY 2029. The EPA is also proposing other
changes to the test protocols used to evaluate emissions performance
for certification and related regulatory issues. Potential amendments
to the Tier 4 standards and other program elements will be proposed
separately in a future Part 2 rulemaking.
DATES:
Comments. Comments must be received on or before July 6, 2026, at
11:59 p.m. Eastern Time. Comments on the information collection
provisions submitted to the Office of Management and Budget (OMB) under
the Paperwork Reduction Act (PRA) are best assured of consideration by
OMB if OMB receives a copy of your comments on or before July 6, 2026.
Public Hearing. The EPA plans to hold a public hearing for this
proposal on June 3 and 4, 2026. Please refer to the SUPPLEMENTARY
INFORMATION section for additional information on the public hearing.
ADDRESSES: You may send comments, identified by Docket ID No. EPA-HQ-
OAR- 2025-3297, by any of the following methods:
[[Page 28464]]
Federal eRulemaking Portal: https://www.regulations.gov
(our preferred method). Follow the online instructions for submitting
comments. Pursuant to the Administrative Procedure Act at 5 U.S.C.
553(b)(4), a plain language summary of the rule is also available on
the Federal eRulemaking Portal.
Email: [email protected]. Include Docket ID No. EPA-
HQ-OAR-2025-3297 in the subject line of the message.
Mail: U.S. Environmental Protection Agency, EPA Docket
Center, Docket ID No. EPA-HQ-OAR- 2025-3297, Mail Code 28221T, 1200
Pennsylvania Avenue NW, Washington, DC 20460.
Hand/Courier Delivery: EPA Docket Center, WJC West
Building, Room 3334, 1301 Constitution Avenue NW, Washington, DC 20004.
The Docket Center's hours of operation are 8:30 a.m.-4:30 p.m., Monday-
Friday (except Federal holidays). Comments received may be posted
without change to https://www.regulations.gov, including any personal
information provided. For detailed instructions on sending comments,
see the ``Public Participation'' heading of the SUPPLEMENTARY
INFORMATION section of this document.
FOR FURTHER INFORMATION CONTACT: For information about this proposed
rule, contact Dr. John J. Kasab, Office of Transportation and Air
Quality, U.S. Environmental Protection Agency, 2000 Traverwood Drive,
Ann Arbor, Michigan 48105; telephone number (734) 214-4559; and email
address: [email protected]. Individuals who are deaf or hard of
hearing, as well as individuals who have speech or communication
disabilities, may use a relay service. To learn more about how to make
an accessible telephone call to any of the numbers shown in this
document, visit the web page for the relay service of the Federal
Communications Commission.
SUPPLEMENTARY INFORMATION:
A. Public Participation
Written Comments. Comments must be received on or before July 6,
2026, at 11:59 p.m. Eastern Time. All information will be available for
inspection at the EPA Air Docket No. EPA-HQ-OAR-2025-3297. Submit your
comments, identified by Docket ID No. EPA-HQ-OAR-2025-3297, at https://www.regulations.gov (our preferred method), or the other methods
identified in the ADDRESSES section. Once submitted, comments cannot be
edited or removed from the docket. The EPA may publish any comment
received to the Agency's public docket.
The written comment is considered the official comment and should
include discussion of all points you wish to make. The EPA will
generally not consider comments or comment contents located outside of
the primary submission (i.e., on the web, cloud, or other file sharing
system). For additional submission methods, the full EPA public comment
policy, information about Confidential Business Information (CBI) or
multimedia submissions, and general guidance on making effective
comments, please visit https://www.epa.gov/dockets/commenting-epa-
dockets.
Submitting Confidential Business Information. Do not submit
information containing CBI to the EPA through https://www.regulations.gov. Clearly mark the part or all the information that
you claim to be CBI. For CBI on any digital storage media that you mail
to the EPA, note the docket ID, mark the outside of the digital storage
media as CBI, and identify electronically within the digital storage
media the specific information that is claimed as CBI. In addition to
one complete version of the comments that includes information claimed
as CBI, you must submit a copy of the comments that does not contain
the information claimed as CBI directly to the public docket through
the procedures outlined in the Public Participation section of this
document. If you submit any digital storage media that does not contain
CBI, mark the outside of the digital storage media clearly so that it
does not contain CBI and note the docket ID. Information not marked as
CBI will be included in the public docket and the EPA's electronic
public docket without prior notice. Information marked as CBI will not
be disclosed except in accordance with procedures set forth in the Code
of Federal Regulations (CFR), Title 40, part 2.
Our preferred method to receive CBI is electronic transmission
using email attachments, File Transfer Protocol (FTP), or other online
file sharing services (e.g., Dropbox, OneDrive, Google Drive).
Electronic submissions must be transmitted directly to the person
listed in the FOR FURTHER INFORMATION CONTACT section. If sending CBI
information through the postal service, please send it to the person
listed in the FOR FURTHER INFORMATION CONTACT section and add
``Attention Docket ID No. EPA-HQ-OAR-2025-3297.'' The mailed CBI
material should be double wrapped and clearly marked. Any CBI markings
should not show through the outer envelope.
Public Hearing. The EPA will hold a public hearing on this proposal
on June 3 and 4, 2026. If there is sufficient interest, an additional
day of hearings will be held on the subsequent day. Information on the
public hearing is available at https://www.epa.gov/regulations-emissions-vehicles-and-engines/revision-tier-4-phase-schedule-light-duty-and-medium. Please also refer to this website for any updates
regarding the hearings. The EPA does not intend to publish additional
documents in the Federal Register announcing updates.
Please sign up for a speaking slot by emailing [email protected]. Note that each speaker will get three (3) minutes to
speak.
B. Does this action apply to me?
Entities potentially affected by this proposed rule include light-
duty vehicle manufacturers, independent commercial importers,
alternative fuel converters, and manufacturers and converters of
medium-duty vehicles (i.e., vehicles between 8,501 pounds and 14,000
pounds gross vehicle weight rating (GVWR)). Potentially affected
categories and entities include those shown in Table 1.
Table 1--Potentially Affected Categories and Entities
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Examples of potentially
Category NAICS codes\a\ affected entities
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Industry....................... 336111 Motor Vehicle
336112 Manufacturers.
Industry....................... 811111 Commercial Importers of
811112 Vehicles and Vehicle
88898 Components.
423110
Industry....................... 335312 Alternative Fuel
811198 Vehicle Converters.
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Industry....................... 333618 On-highway medium-duty
336120 engine & vehicle
336211 (8,501-14,000 pounds
336312 GVWR) manufacturers.
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\a\ North American Industry Classification System (NAICS).
This list is not intended to be exhaustive but rather provides a
guide regarding entities likely to be affected by this action. To
determine whether particular activities may be regulated by this
action, you should carefully examine the regulations. You may direct
questions regarding the applicability of this action to the person
listed in the FOR FURTHER INFORMATION CONTACT section.
C. Document Information
Preamble acronyms and abbreviations. Throughout this document the
use of ``we,'' ``us,'' or ``our'' is intended to refer to the EPA. We
use multiple acronyms and terms in this preamble. While this list may
not be exhaustive, to ease the reading of this preamble and for
reference purposes, the EPA defines the following terms and acronyms as
follows:
ABT Averaging, banking, and trading
ACC II Advanced Clean Cars II
APA Administrative Procedure Act
AV Annualized value
BEV Battery electric vehicle
BPT Benefit per ton
CAA Clean Air Act
CAFE Corporate Average Fuel Economy
CBI Confidential Business Information
CFR Code of Federal Regulations
CO Carbon monoxide
CRA Congressional Review Act
CY Calendar year
DRIA Draft Regulatory Impact Analysis
E.O. Executive Order
EPA U.S. Environmental Protection Agency
EV Electric vehicle, a.k.a., battery electric vehicle
FR Federal Register
FUL Full useful life
GCWR Gross combination weight rating
GHG Greenhouse gas
GPF Gasoline particulate filter
GVWR Gross vehicle weight rating
HCHO Formaldehyde
HEV Hybrid electric vehicle
ICE Internal combustion engine
LDV Light-duty vehicle, a.k.a. passenger car
LDT Light-duty truck
LMDV Light- and medium-duty vehicle
MDPV Medium-duty passenger vehicle
MDV Medium-duty vehicle
MOVES Motor Vehicle Emissions Simulator model
MY Model year
NAAQS National Ambient Air Quality Standards
NMOG Non-methane organic gases
NOX Nitrogen oxides, a.k.a. oxides of nitrogen
NPRM Notice of proposed rulemaking
NTTAA National Technology Transfer and Advancement Act
OBBB One Big Beautiful Bill Act
OBD On-board diagnostics
OMB Office of Management and Budget
PHEV Plug-in hybrid electric vehicle
PM Particulate matter
PRA Paperwork Reduction Act
PV Present value
RFA Regulatory Flexibility Act
RIA Regulatory Impact Analysis
SFTP Supplemental Federal Test Procedure
TWC Three-way catalytic converter
UMRA Unfunded Mandates Reform Act
U.S. United States of America
U.S.C. United States Code
VOC Volatile organic compounds
Table of Contents
I. Executive Summary
A. Background for This Proposed Rule
B. Summary of This Part 1 Proposed Rule
C. Summary of the Basis and Justification for This Proposal
II. Proposed Amendments to Light- and Medium-Duty Vehicle Tier 4
Phase-In Schedules for Model Years 2027 and 2028
A. Introduction and Background
B. Why is the EPA proposing these amendments?
C. Automotive Vehicle Development Cycle Lead Time Considerations
D. Expected Manufacturer Response with Lower BEV Projections
E. What is the EPA proposing to change?
F. The EPA's Clean Air Act Authority for this Proposal
G. Reliance Interests
III. What are the projected impacts of this proposed rule?
A. What approach did the EPA use in analyzing this proposal?
B. What are the projected changes in costs?
C. What are the projected changes in emissions?
D. What are the projected changes in air quality?
E. What are the projected changes in human health and welfare?
IV. Request for Comment
V. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
B. Executive Order 14192: Unleashing Prosperity Through
Deregulation
C. Paperwork Reduction Act (PRA)
D. Regulatory Flexibility Act (RFA)
E. Unfunded Mandates Reform Act of 1995 (UMRA)
F. Executive Order 13132: Federalism
G. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
H. Executive Order 13045: Protection of Children From
Environmental Health Risks and Safety Risks
I. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
J. National Technology Transfer and Advancement Act (NTTAA) and
1 CFR Part 51
VI. Statutory Authority and List of Subjects
I. Executive Summary
The EPA is proposing to revise the criteria pollutant emission
standards applicable to MYs 2027 and 2028 light-duty vehicles (LDVs),
light-duty trucks (LDTs), medium-duty passenger vehicles (MDPVs), and
medium-duty vehicles (MDVs) (collectively, ``light- and medium-duty
vehicles'') pursuant to Clean Air Act (CAA) section 202(a). If
finalized as proposed, the criteria pollutant emission standards
established for MYs 2025 and beyond in the 2014 Tier 3 Rule \1\ would
apply to MYs 2027 and 2028, and the criteria pollutant emission
standards established in the 2024 Tier 4 Rule \2\ would be delayed
until MY 2029.\3\
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\1\ See ``Control of Air Pollution From Motor Vehicles: Tier 3
Motor Vehicle Emission and Fuel Standards,'' 79 FR 23414 (Apr. 28,
2014) (``2014 Tier 3 Rule'').
\2\ See ``Multi-Pollutant Emissions Standards for Model Years
2027 and Later Light-Duty and Medium-Duty Vehicles,'' 89 FR 27842
(Apr. 18, 2024) (``LMDV Multipollutant Rule'').
\3\ In this proposed rule, ``criteria pollutants'' refers
generally to criteria pollutants and their precursors, including
tailpipe non-methane organic gases (NMOG), oxides of nitrogen
(NOX), particulate matter (PM), and carbon monoxide (CO),
as well as evaporative and refueling hydrocarbons.
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Under CAA section 202(a), the EPA promulgates standards for the
emission of air pollutants from new motor vehicles which, in the
Administrator's judgment, cause or contribute to air pollution which
may reasonably be anticipated to endanger public health or welfare.\4\
The standards can take effect only ``after such period as the
Administrator finds necessary to permit the development and application
of the requisite technology, giving appropriate
[[Page 28466]]
consideration to the cost of compliance within such period.'' \5\ Thus,
in establishing or revising standards under CAA section 202(a), the EPA
also must consider issues of technological feasibility, the cost of
compliance, and lead time, among other relevant considerations.
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\4\ 42 U.S.C. 7521(a)(1).
\5\ 42 U.S.C. 7521(a)(2).
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In this action, the EPA proposes to extend the Tier 3 standards
applicable to MYs 2026 and beyond light- and medium-duty vehicles to
MYs 2027 and 2028, thereby delaying the initial applicability of Tier 4
standards, to address recent developments and information before the
Agency suggesting serious technical and feasibility concerns with
compliance in the near term. Given the short time available for
compliance with respect to MYs 2027 and 2028, the EPA believes that
changes to the substance of the Tier 4 standards themselves would not
be a feasible or appropriate way to address the technical and
feasibility concerns described in this preamble and is limiting this
proposal to extending the existing Tier 3 standards for MYs 2025 and
beyond, which are familiar to regulated parties, to MYs 2027 and 2028.
Potential changes to the Tier 4 standards will be addressed in a future
rulemaking. The EPA seeks comment on all aspects of this proposed rule
and looks forward to engagement with interested stakeholders as part of
the Agency's regulatory development process.
A. Background for This Proposed Rule
On April 28, 2014, the EPA published criteria pollutant emission
standards for light- and medium-duty vehicles pursuant to CAA section
202(a). These standards set emission limitations for criteria
pollutants beginning in MY 2017 that increased in stringency on an
annual basis and concluded with the most stringent Tier 3 standards
applicable to MYs 2025 and later vehicles. The Tier 3 standards
required, as a general matter, a 70-80 percent reduction in criteria
pollutant emissions for MYs 2025 and beyond LD vehicles as compared to
MY 2017 vehicles.\6\
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\6\ See 79 FR 23417 (Apr. 28, 2014).
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On April 18, 2024, the EPA published multipollutant emissions
standards for light- and medium-duty vehicles pursuant to CAA section
202(a). The LMDV Multipollutant Rule established new, more stringent
vehicle emissions standards for both criteria pollutant and greenhouse
gas (GHG) emissions for MY 2027 through MY 2032 and beyond. The EPA
refers to those criteria pollutant standards and program elements as
the Tier 4 standards or the Tier 4 program. The non-methane organic
gases and oxides of nitrogen (NMOG+NOX) standards for light-
and medium-duty vehicles were established based on a projected high
market share of battery electric vehicles (BEVs), as the expected high
BEV volumes would participate in the emissions averaging for
NMOG+NOX, thus enabling a manufacturer to meet the Tier 4
NMOG+NOX standards as they decreased to the final fleet-
averaged values in MY 2032 or 2033.\7\
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\7\ On Feb. 18, 2026, the EPA published a final rule that
rescinded the GHG emission standards contained in the LMDV
Multipollutant Rule but did not reopen or amend the criteria
pollutant emission standards. See ``Rescission of the Greenhouse Gas
Endangerment Finding and Motor Vehicle Greenhouse Gas Emission
Standards Under the Clean Air Act,'' 91 FR 7686 (Feb. 18, 2026)
(``EF/GHG Final Rule''). Note that any comments related to the EF/
GHG Final Rule are considered out of scope for this proposal.
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B. Summary of This Part 1 Proposed Rule
In this Part 1 rulemaking, the EPA is proposing to delay the phase-
in of the Tier 4 criteria pollutant standards promulgated in the LMDV
Multipollutant Rule for light- and medium-duty vehicles to address
changed circumstances and feasibility concerns. Specifically, this
action would extend the Tier 3 program through MYs 2027 and 2028 for
both light- and medium-duty vehicles by proposing to replace the
mandatory Tier 4 standards for light- and medium-duty vehicles up to
6,000 pounds GVWR and proposing to remove the optional Tier 4 standards
for light- and medium-duty vehicles over 6,000 pounds GVWR. The EPA is
also proposing to delay to MY 2029 changes to the test protocols used
to evaluate emissions performance for certification. In the future Part
2 rulemaking, the EPA will comprehensively reconsider the Tier 4
program for light- and medium-duty vehicles, which may include, for
example, changes to the Tier 4 emission standards, lead time and phase-
in schedule, and test procedures.
C. Summary of the Basis and Justification for This Proposal
In this Part 1 rulemaking, the EPA is proposing to extend the Tier
3 standards for two additional MYs based on the Agency's consideration
of the statutory factors in CAA section 202(a)(2), which requires that
new or revised standards ``shall take effect after such period as the
Administrator finds necessary to permit the development and application
of the requisite technology, giving appropriate consideration to the
cost of compliance within such period.'' \8\ The EPA is extending the
Tier 3 standards and thus delaying the Tier 4 standards primarily due
to concerns with lead time, that is, the time ``necessary to permit the
development and application of the requisite technology.'' The Tier 4
standards were predicated on projected high BEV market penetration. In
the case of the NMOG+NOX declining fleet average standard,
BEVs are averaged into the fleet at zero grams per mile, thus reducing
the fleet average NMOG+NOX standard of any manufacturer that
produces and sells BEVs. The higher the sales of BEVs for a given MY,
the lower the manufacturer's fleet average NMOG+NOX standard
performance. In the case of PM standards, BEVs would not require any
added PM equipment as their PM tailpipe emissions are zero grams per
mile. Given that the Tier 4 p.m. standards are phased in at the rate of
20 percent in MY 2027 and 40 percent in MY 2028, high BEV sales would
mean that many manufacturers would require fewer, and potentially no,
additional PM controls on their conventional gasoline vehicles to
comply with the phase-in requirements. Collectively, this meant that
manufacturers did not plan on the need to reduce emissions from non-BEV
vehicles for MYs 2027 and 2028 to any significant degree. Manufacturers
correspondingly built their product mix and compliance strategies on
this assumption, which reflected the EPA's predictive judgments at the
time about trends relevant to the feasibility of the Tier 4 standards.
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\8\ 42 U.S.C. 7521(a)(2).
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Since the promulgation of the Tier 4 standards in April 2024,
significant changes in the automotive marketplace, regulations, and
Federal and State laws have substantially impacted manufacturers'
future product plans for light- and medium-duty vehicles, particularly
the development, production, and sales of BEVs. Recent legislation,
including the June 2025 Congressional Review Act (CRA) resolution
voiding the EPA's preemption waiver for California's Advanced Clean
Cars II (ACC II) standards \9\ and the One Big Beautiful Bill Act
(OBBB) \10\ enacted in July 2025,
[[Page 28467]]
contributed to a change in consumer demand and production choices and
has impacted near-term projections of BEV market share from what the
EPA considered when developing the Tier 4 standards in the LMDV
Multipollutant Rule. In addition, domestic and global macroeconomic
factors that are expected to impact vehicle purchase decisions have
changed since the EPA issued the LMDV Multipollutant Rule, both in
terms of timing and in terms of types of vehicles consumers are likely
to purchase.
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\9\ See ``Providing congressional disapproval under chapter 8 of
title 5, United States Code, of the rule submitted by the
Environmental Protection Agency relating to `California State Motor
Vehicle and Engine Pollution Control Standards; Advanced Clean Cars
II; Waiver of Preemption; Notice of Decision,' '' Public Law 119-16,
June 12, 2025, 139 Stat. 66.
\10\ See ``An act to provide for reconciliation pursuant to
title II of H. Con. Res. 14.'' (``One Big Beautiful Bill Act,'' or
OBBB), Pubic Law 119-21, July 4, 2025, 139 Stat. 72. Specifically,
OBBB ends incentives such as the 30D tax credits for purchasing BEVs
earlier than originally scheduled. The EPA considered these
incentives in developing the LMDV Multipollutant Rule. Other
incentives that would have facilitated BEV adoption were also ended
early by the OBBB.
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In light of these changes, the EPA now projects that the share of
new light-duty BEVs sold in the market will be significantly lower in
MYs 2027 and 2028 than the Agency previously estimated in the LMDV
Multipollutant Rule.\11\ These revised projections are supported by
recent announcements and developments in the industry as detailed in
section II of this preamble. The EPA expects that every manufacturer
that sells a mix of conventional and electric vehicles has been
significantly impacted by these changes. Manufacturers who were
planning to rely on BEVs for Tier 4 standards compliance will be faced
with fewer BEV sales than previously expected and have a limited time
to alter their product plans for MYs 2027 and 2028. Given that zero
emission BEVs significantly assist any fleet average and can eliminate
the need for additional emission controls on non-BEV vehicles,
manufacturers would need to rely on unplanned modifications to large
numbers of non-BEV vehicles to meet the Tier 4 standards. Thus, given
the significant disruption in manufacturer product planning, the EPA
proposes finding that more time is ``necessary to permit the . . .
application of the requisite technology'' into new, compliant
vehicles.\12\
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\11\ See U.S. Environmental Protection Agency. (2026). ``Battery
Electric Vehicle Projected Market Share Analysis.'' EPA-HQ-OAR-2025-
3297.
\12\ 42 U.S.C. 7521(a)(2).
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Manufacturers are now faced with a vastly different compliance
landscape wherein they need to rely on emission reductions from non-BEV
vehicles, rather than increased BEV sales. As a result, EPA is
reconsidering the Tier 4 standards through a two-part rulemaking. This
Part 1 proposal is in recognition that the impacts of the past two
years on the automotive industry are significant enough that the EPA
believes the start of the Tier 4 program should be delayed by two MYs.
The EPA proposes a two-year delay based on industry practices that
indicate a year to 18 months would be necessary to adjust production
plans, and the industry has not had sufficient time to respond to the
enormous changes in the BEV landscape, and companies' ability to comply
with Tier 4 for MYs 2027 and 2028 are in jeopardy. The EPA is therefore
proposing to extend the Tier 3 program by two additional MYs. In
parallel, but with a longer timeline, the EPA will develop the Tier 4
reconsideration Part 2 rulemaking. In the future Part 2 rulemaking, the
EPA will comprehensively reconsider the Tier 4 program for light- and
medium-duty vehicles, which may include, for example, changes to the
Tier 4 emission standards, lead time and phase-in schedule, and test
procedures. This proposed Part 1 rulemaking, if finalized, would allow
manufacturers to continue meeting the Tier 3 standards for two more
years while the EPA develops the Part 2 rule, which may amend the Tier
4 program for later MYs. Vehicle manufacturers are already in
compliance with the Tier 3 program, so extending the Tier 3
requirements should be technically feasible and minimally disruptive to
their current plans. Aligning other provisions beyond standards, such
as test procedures, with Tier 3 requirements allows manufacturers to
continue with the well-known Tier 3 procedures while they develop non-
BEV products to comply with the updated Tier 4 procedures.
II. Proposed Amendments to Light- and Medium-Duty Vehicle Tier 4 Phase-
In Schedules for Model Years 2027 and 2028
A. Introduction and Background
On April 28, 2014, the EPA promulgated standards under CAA section
202(a) for criteria pollutant emissions from light-duty and medium-duty
vehicles in its 2014 Tier 3 Rule.\13\ The EPA subsequently published
the LMDV Multipollutant Rule on April 18, 2024, which introduced, among
other provisions, the Tier 4 criteria pollutant standards for
NMOG+NOX, PM, CO, and formaldehyde (HCHO). The Tier 4
standards also include changes to the test cycles used to evaluate
emissions performance for certification and other items, such as high-
altitude standards for NMOG+NOX.
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\13\ See ``Control of Air Pollution From Motor Vehicles: Tier 3
Motor Vehicle Emission and Fuel Standards,'' 79 FR 23414 (Apr. 28,
2014) (``2014 Tier 3 Rule'').
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The Tier 4 standards are currently scheduled to go into effect in
MY 2027, starting with light-duty program vehicles (i.e., LDVs, LDTs,
and MDPVs) that are up to 6,000 pounds GVWR. CAA section 202(a)(3)(C)
states that revised standards for ``heavy-duty'' vehicles, defined as
those vehicles over 6,000 pounds GVWR, be subject to three MYs of
stability and four MYs of lead time.\14\ In following with these CAA
requirements, the standards for light-duty program vehicles up to 6,000
pounds GVWR follow a declining fleet average standard for
NMOG+NOX that decreases from the Tier 3 fleet average of 30
milligrams per mile (mg/mile) in MY 2026 to 15 mg/mile by MY 2032, a 50
percent reduction in NMOG+NOX standards.\15\ Manufacturers
may choose to have their light-duty program vehicles over 6,000 pounds
GVWR follow either the default, single-step phase-in in MY 2030 or
follow an optional early phase-in schedule that aligns with that of
light-duty program vehicles up to 6,000 pounds GVWR.\16\
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\14\ While the EPA applies several regulatory classes (LDV, LDT,
MDPV, MDV) in the structure of its Tier 3 and Tier 4 programs, LDVs
and MDVs have different phase-in and lead-time provisions under the
CAA based on their GVWR. Per CAA section 202(b)(3)(C), a vehicle
with a GVWR over 6,000 pounds is considered a ``heavy duty
vehicle,'' and per CAA section 202(a)(3)(C) standards promulgated
for these vehicles ``shall apply for a period of no less than 3
model years beginning no earlier than the model year commencing 4
years after such revised standard is promulgated.'' Vehicles up to
6,000 pounds GVWR are not subject to lead time or stability
constraints. See 40 CFR 86.1811-17 (for Tier 3) and 40 CFR 86.1811-
27 (for Tier 4). 40 CFR 86.1803-01 provides the definitions that
classify these vehicles necessary to apply the weight-based rules.
\15\ See 2014 Tier 3 Rule and Table 39 of LMDV Multipollutant
Rule at 89 FR 27935. Note that the default option for heavier LDVs
of 6,001-8,500 pounds reduces the fleet average NMOG+NOX
standard from 30 mg/mile in MY 2029 to 15 mg/mile in MY 2030.
\16\ See Table 39, LMDV Multipollutant Rule at 89 FR 27935 (Apr.
18, 2024).
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For MDVs, the EPA finalized Tier 4 NMOG+NOX standards
that step down the fleet average level to 75 mg/mile starting in MY
2031, representing a 58 percent reduction from the Tier 3 standard of
178 mg/mile for Class 2b vehicles and a 70 percent reduction from the
Tier 3 standard of 247 mg/mile for Class 3 vehicles.\17\ MDVs may
follow either the default, single-step phase-in in MY 2031 or an
optional early phase-in schedule.\18\
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\17\ See Table 42 of LMDV Multipollutant Rule at 89 FR 27937
(Apr. 18, 2024).
\18\ See Tables 41 and 42, LMDV Multipollutant Rule at 89 FR
27937 (Apr. 18, 2024).
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The NMOG+NOX standards for light- and medium-duty
vehicles were
[[Page 28468]]
established based on a projected high market share of BEVs, as the
expected high BEV volumes would participate in the emissions averaging
for NMOG+NOX. This BEV share would enable a firm to meet the
Tier 4 NMOG+NOX standards. The EPA also finalized a cold
ambient temperature (-7 [deg]C) NMOG+NOX standard for all
light- and medium-duty vehicles and eliminated the Supplemental Federal
Test Procedure (SFTP) to reduce emissions over a broad range of
operating conditions.
For all light- and medium-duty vehicles, the EPA also finalized a
PM standard of 0.5 mg/mile and a requirement that the standard be met
across three test cycles, including a cold temperature test (-7 [deg]C
Federal Test Procedure (FTP)-75) and a high-speed highway driving test
(US06). This standard supplanted the existing PM standard of 3 mg/mile
established in the 2014 Tier 3 Rule for light-duty program vehicles and
higher PM standards for MDVs. The revised PM standards are projected to
result in the broad adoption of gasoline particulate filters (GPF) on
all gasoline vehicles.
In the LMDV Multipollutant Rule, the EPA also finalized in-use
standards for MDVs with high gross combination weight rating (GCWR),
changes to MDV refueling emissions requirements for incomplete
vehicles, and several other NMOG+NOX provisions. The EPA
also finalized changes to the CO and HCHO standards for light- and
medium-duty vehicles, including at -7 [deg]C.
These schedules for light- and medium-duty vehicles are summarized
in Table 2, where each value represents the minimum fraction of
vehicles that must be certified to the Tier 4 standards.\19\ If the
value is less than 100 percent, the remaining new vehicles may be
certified as interim Tier 4 vehicles. An interim Tier 4 vehicle is a
vehicle that is produced during the phase-in years and does not meet
the Tier 4 standards, but rather meets the Tier 3 standards.
---------------------------------------------------------------------------
\19\ See Tables 33 and 35, LMDV Multipollutant Rule at 89 FR
27930 and 27932 (Apr. 18, 2024), respectively.
Table 2--Tier 4 Light-Duty and Medium-Duty Vehicle Criteria Pollutant Phase-In Schedules
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vehicle GVWR 6001-8500 lb and MDPV MDV (GVWR 8501-14000 lb)
Model year Vehicle GVWR ---------------------------------------------------------------------------
<=6000 lb (%) Default (%) Early option (%) Default (%) Early option (%)
--------------------------------------------------------------------------------------------------------------------------------------------------------
2027..................................................... 20 0 20 0 20
2028..................................................... 40 0 40 0 40
2029..................................................... 60 0 60 0 60
2030..................................................... 100 100 100 0 80
2031..................................................... 100 100 100 100 100
--------------------------------------------------------------------------------------------------------------------------------------------------------
MDV refers to medium-duty vehicle, which is a combination of both Class 2b and 3 vehicles as defined in 40 CFR 86.1803-01.
The Tier 4 standards include per-vehicle standards for PM, CO, and
HCHO and a fleet average standard for NMOG+NOX. The Tier 3
and Tier 4 p.m. standards are shown in Table 3, while the Tier 4 CO and
HCHO standards are shown in Table 4.\20\ NMOG+NOX standards
are shown later in this section.
---------------------------------------------------------------------------
\20\ See Tables 43, 44, 45, and 46, LMDV Multipollutant Rule at
89 FR 27939, 27939, 27947, and 27948 (Apr. 18, 2024), respectively.
Table 3--Tier 3 and Tier 4 Light-Duty and Medium-Duty Vehicle PM Standards
----------------------------------------------------------------------------------------------------------------
LDV, LDT, MDPV PM standards (mg/mi) MDV (Class 2b and 3) PM standards (mg/
--------------------------------------- mi)
Test cycle --------------------------------------
Tier 3 Tier 4 Tier 3 Tier 4
----------------------------------------------------------------------------------------------------------------
25 [deg]C FTP..................... 3.................... 0.5 8 for Class 2b....... 0.5
10 for Class 3.......
US06.............................. 6.................... 0.5 10 for Class 2b on 0.5
SFTP.
7 for Class 3 on SFTP
-7 [deg]C FTP..................... Not applicable....... 0.5 Not applicable....... 0.5
----------------------------------------------------------------------------------------------------------------
Table 4--Tier 4 Light-Duty and Medium-Duty Vehicle CO and HCHO Emission
Standards
------------------------------------------------------------------------
Per-vehicle emission standards LDV, LDT, MDPV MDV
------------------------------------------------------------------------
CO std. for 25 [deg]C FTP, HFET, SC03 (g/ 1.7 3.2
mile)..................................
CO std. for US06 (g/mile)............... 9.6 25
CO std. for -7 [deg]C FTP (g/mile)...... 10.0 10.0
HCHO std. for 25 [deg]C FTP (mg/mile)... 4 6
------------------------------------------------------------------------
In addition to the differences between Tier 3 and Tier 4 per-
vehicle criteria pollutant standards shown in Table 3, there are
differences in certification requirements. These differences are
summarized in Table 5.
[[Page 28469]]
Table 5--Comparison of Selected Tier 3 and Tier 4 Requirements
------------------------------------------------------------------------
Tier 3 (Interim Tier
Item 4) Tier 4
------------------------------------------------------------------------
Main test cycle \a\......... 25 [deg]C FTP-75.... 25 [deg]C FTP-75.
Supplemental FTP \a\........ Weighted average of Separate US06 and -7
FTP-75, SC03, and [deg]C FTP-75
US06. For Class 3 measurements for
MDV use FTP-75, NMOG+NOX; US06, for
SC03, and LA-92. CO and PM; Use US06
for Class 3 MDV.
PM standards................ Measured on 25 Measured on -7
[deg]C FTP-75 and [deg]C FTP-75, 25
US06. [deg]C FTP-75, and
US06.
Additional tests............ .................... Early drive-away and
mid-temperature
engine starts. High-
power cold start
for PHEV.\a\
NMOG+NOX bin structure...... Bins 0, 20, 30, 50, Bins 0, 5, 10, 15,
70, 125, 160. 20, 25, 30, 35, 40,
45, 50, 55, 60, 65,
70.
Additional MDV bins......... 150, 170, 200, 230, 75, 85, 100, 125,
250, 270, 340, 400, 150, 170.
570.
High altitude NMOG+NOX Relaxed NMOG+NOX Same NMOG+NOX result
requirements (1,620 m). standard at high required at high
altitude, e.g., 50 altitude as at low
mg/mi for Bin 30. altitude.
------------------------------------------------------------------------
\a\ The 25 [deg]C FTP-75, -7 [deg]C FTP -75, LA-92, SC03, and US06 drive
cycles are all defined in Appendix I of 40 CFR part 86. Plug-in Hybrid
Electric Vehicle (PHEV).
The Tier 4 light-duty program vehicle phase-in schedules of sales-
weighted fleet average NMOG+NOX standards are shown in Table
6 with the Tier 3 standard in MY 2026 included for reference.\21\ The
sales-weighted fleet average NMOG+NOX standards for MDVs are
shown in Table 7.\22\ Note that the PM, CO, and HCHO standards are per-
vehicle standards subject to the phase-in schedules shown in Table 2
whereas the NMOG+NOX standards represent fleet averages and
follow the phase-in schedules shown in Tables 6 and 7.
---------------------------------------------------------------------------
\21\ See Table 39, LMDV Multipollutant Rule at 89 FR 27935 (Apr.
18, 2024).
\22\ See Tables 41 and 42, LMDV Multipollutant Rule at 89 FR
27937 (Apr. 18, 2024).
Table 6--Tier 4 LDV, LDT, and MDPV Fleet Average NMOG+NOX Standards
----------------------------------------------------------------------------------------------------------------
LDV, LDT1-2 (GVWR LDT3-4 (GVWR 6,001-8,500 lb) and MDPV NMOG+NOX
<=6,000 lb) NMOG+NOX (mg/mi.)
Model year (mg/mi.) -------------------------------------------------
-------------------------
Default Default Early option
----------------------------------------------------------------------------------------------------------------
2026 \a\............................. \a\ 30 \a\ 30 \a\ 30
2027................................. 25 30 25
2028................................. 23 30 23
2029................................. 21 30 21
2030................................. 19 15 19
2031................................. 17 15 17
2032 and later....................... 15 15 15
----------------------------------------------------------------------------------------------------------------
\a\ Tier 3 standards provided for reference.
Table 7--Tier 4 MDV Fleet Average NMOG+NOX Standards
--------------------------------------------------------------------------------------------------------------------------------------------------------
Class 2b NMOG+NOX (mg/mi) Class 3 NMOG+NOX (mg/mi)
Model year ---------------------------------------------------------------------------------------------------
Default Early option Default Early option
--------------------------------------------------------------------------------------------------------------------------------------------------------
2026 \a\............................................ \a\ 178 \a\ 178 \a\ 247 \a\ 247
2027................................................ 178 175 247 175
2028................................................ 178 160 247 160
2029................................................ 178 140 247 140
2030................................................ 178 120 247 120
2031 \b\............................................ 75 100 75 100
2032 \b\............................................ 75 80 75 80
2033 and later \b\.................................. 75 75 75 75
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Tier 3 FTP fleet average standards provided for reference.
\b\ MDV with a GCWR greater than 22,000 pounds must also comply with additional moving average window (MAW) in-use testing requirements.
In addition to changing the numeric standards as shown in Tables 3,
4, 6, and 7, the EPA also expanded the Tier 4 testing requirements to
ensure robust emissions control over a broad range of operating
conditions, such as at cold ambient temperatures or high altitudes.
The EPA expected that vehicle manufacturers would meet the fleet
average standards for NMOG+NOX and per-vehicle standards for
PM, CO, and HCHO through a combination of technologies that included a
significantly increased adoption of BEVs, which certify as emitting
zero
[[Page 28470]]
mg/mile of all tailpipe emissions, and better emissions control
technologies for internal combustion engine (ICE) vehicles, hybrid
electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs).
Further discussion of these technologies can be found in the LMDV
Multipollutant Rule's Regulatory Impact Analysis (``LMDV RIA'') and in
Chapter 2 of the 2023 proposed LMDV Multipollutant Rule's Draft RIA
(``LMDV DRIA'').\23\
---------------------------------------------------------------------------
\23\ See Chapter 3.2.5 at 3-52 of U.S. Environmental Protection
Agency, Regulatory Impact Analysis: Multi-Pollutant Emissions
Standards for Model Years 2027 and Later Light-Duty and Medium-Duty
Vehicles, (March 2024), available at https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P1019VPM.pdf. (``LMDV RIA''); and Chapter 2 of U.S.
Environmental Protection Agency, Draft Regulatory Impact Analysis:
Multi-Pollutant Emissions Standards for Model Years 2027 and Later
Light-Duty and Medium-Duty Vehicles, (April 2023), available at
https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P10175J2.pdf. (``LMDV
DRIA'').
---------------------------------------------------------------------------
B. Why is the EPA proposing these amendments?
As discussed in this proposal, recent changes in policy,
regulations, Federal and State law, and other factors have
significantly changed projections of BEV market share in the coming
MYs. Due to the significant change in the BEV landscape, the EPA is
reconsidering the Tier 4 light- and medium-duty vehicle program in two
separate but coordinated rulemakings, the Part 1 rule and the Part 2
rule. In this Part 1 rule proposal, the EPA is proposing to extend the
Tier 3 program by two MYs (MYs 2027 and 2028). The EPA provides in this
section II.B details regarding the basis for this Part 1 rule proposal.
In the future Part 2 rule, the EPA will comprehensively reconsider the
Tier 4 program for light- and medium-duty vehicles, which may include,
for example, changes to the Tier 4 emission standards, lead time and
phase-in schedule, and test procedures.
1. Changes in Federal and State Policies and Laws Related to Electric
Vehicles and Electric Vehicle Infrastructure Development
The conditions upon which the EPA based the analysis of BEV
adoption rates in the LMDV Multipollutant Rule have changed
significantly due to several factors, including Federal and State
policies and laws related to electric vehicles and electric vehicle
infrastructure development and the Agency's understanding of consumer
interest in BEVs.
In May 2025, Congress passed legislation disapproving the EPA's
preemption waiver for California's ACC II standards; President Trump
signed this legislation into law in June 2025.\24\ Because CAA section
209(a) bars States and localities from adopting or attempting to
enforce non-Federal emission standards for new motor vehicles absent a
valid preemption waiver, this legislation effectively blocks
California's mandate to phase out ICE vehicle sales by 2035. Twelve
other States that previously adopted ACC II pursuant to CAA section 177
can no longer enforce it. The result has been a significant change in
projected demand for BEVs and ICE vehicles resulting from the absence
of this significant regulatory influence.
---------------------------------------------------------------------------
\24\ See ``Providing congressional disapproval under chapter 8
of title 5, United States Code, of the rule submitted by the
Environmental Protection Agency relating to `California State Motor
Vehicle and Engine Pollution Control Standards; Advanced Clean Cars
II; Waiver of Preemption; Notice of Decision,' '' Public Law 119-16,
139 Stat. 66 (June 12, 2025); EF/GHG Final Rule.
---------------------------------------------------------------------------
On July 4, 2025, President Trump signed the OBBB, which
significantly changed tax incentives for BEVs.\25\ Specifically, the
OBBB ended incentives such as the 30D tax credits for purchasing BEVs
earlier than originally scheduled. Other incentives, such as the 25E
Previously-Owned Clean Vehicle Credit and the 45W Commercial Clean
Vehicle Credit, that were predicted to facilitate BEV adoption were
also ended early by the OBBB. The EPA considered and relied on these
incentives to estimate BEV market share in developing the LMDV
Multipollutant Rule. These actions are projected to significantly
reduce new BEV sales for future MYs, including MYs 2027 and 2028, as
described in the following paragraph.
---------------------------------------------------------------------------
\25\ See OBBB.
---------------------------------------------------------------------------
Collectively, these changes are expected to significantly affect
the ability of manufacturers to comply with the Tier 4 standards. In
the LMDV Multipollutant Rule, the central analysis case projections for
BEV market share for all light-duty program vehicles in MYs 2027 and
2028 were 26 and 31 percent, respectively, and for vehicles up to 6,000
pounds, 28 and 33 percent, respectively.\26\ By contrast, for this
proposal, the EPA projects the overall BEV market share values are
eight percent in MY 2027 and 12 percent in MY 2028.\27\ These values
are consistent with recent projections from Bloomberg New Energy
Finance, J.D. Power, Auto Pacific, and Ford Motor Company, as discussed
in section III.A of this preamble. The 8 and 12 percent BEV market
shares in MYs 2027 and 2028, respectively, are relevant to Tier 4
compliance because BEVs certify with zero mg/mile emissions.
Nevertheless, each manufacturer would need to apply Tier 4 compliance
technology to a portion of their MYs 2027 and 2028 ICE vehicles to meet
the Tier 4 program phase-in requirements under current projections.
Specifically, 12 percent of vehicles up to 6,000 pounds would need to
have ICE Tier 4 compliance technology in MY 2027 to reach a total of 20
percent final Tier 4 compliant vehicles, and 28 percent in MY 2028 to
reach 40 percent final Tier 4 compliant vehicles.
---------------------------------------------------------------------------
\26\ See Table 3 of LMDV Multipollutant Rule at 27856 and Tables
12-64 and 12-65 of the LMDV RIA at 12-35 and 12-36, respectively.
\27\ See U.S. Environmental Protection Agency. (2026). ``Battery
Electric Vehicle Projected Market Share Analysis.'' EPA-HQ-OAR-2025-
3297.
---------------------------------------------------------------------------
The EPA believes that manufacturers that based their compliance
strategies with the Tier 4 standards in whole or in part on plans for
increased development and sales of BEVs now need to reconfigure their
compliance plans, which can entail changes in future product
development, vehicle sales mix, vehicle technology, and vehicle
marketing. A two-year extension of the Tier 3 program is needed to
ensure the industry can comply with the EPA's emission standards.
2. Impact of Policy Changes on Compliance With Tier 4 Standards
As discussed above, in the LMDV Multipollutant Rule, the EPA
projected significant adoption of BEVs in future MYs, including MYs
2027 and 2028. The EPA projected that the increase in BEVs in future
MYs would contribute to automakers' ability to meet Tier 4 standards.
The EPA Tier 4 standards for NMOG+NOX emissions from light-
and medium-duty vehicles use sales-weighted fleet averages. This
regulatory approach recognizes that manufacturers may use a mixture of
ICE vehicles (including HEVs and PHEVs), and BEVs to meet the
standards. The EPA projected that the increase in BEVs in future MYs
would contribute to automakers' ability to meet the NMOG+NOX
standards. Each BEV counts as a zero for emissions in the
NMOG+NOX fleet average standard. Therefore, the BEV market
share affects how many ICE, HEV, and PHEV vehicles need technology
improvement to further reduce NMOG+NOX emissions. The EPA
projected, and many manufacturers assumed, that manufacturers would be
able to comply with this fleet average standard primarily with BEV
sales. BEV market share also affects how vehicles manufacturers meet
the per-vehicle standards for other pollutants. For example, since BEVs
have zero tailpipe PM emissions, any BEV sold would
[[Page 28471]]
count toward the per-vehicle phase-in requirement for PM, essentially
meaning manufacturers would have to install fewer GPFs on gasoline ICE
vehicles to reduce PM to the Tier 4 standard. In other words, if the
phase-in schedule required 20 percent compliance with Tier 4 per-
vehicle standards in MY 2027, and the EPA projected a BEV market share
of 26 percent for light-duty program vehicles for that same MY, a
manufacturer might have heavily or even completely relied on BEVs to
meet that standard. Whereas if BEVs make up a much smaller market
share, it would follow that the same manufacturer might not be able to
achieve compliance in the same manner, and may need to invest in
additional compliance technologies for ICE vehicles on which it did not
initially plan.
BEV market share also affects how manufacturers meet the per-
vehicle standards for other pollutants. Since BEVs have zero tailpipe
PM emissions, any BEV sold would count toward the per-vehicle phase-in
requirement for PM, essentially meaning manufacturers would have to
install fewer GPFs on gasoline ICE vehicles to reduce PM to the Tier 4
standard.
3. Automaker Response to Changes in the BEV Landscape
Many major automakers are adjusting their BEV development and
production strategies based on policy, legislative, regulatory, and
marketplace changes that have impacted consumer demand. This level of
change creates significant challenges for manufacturers not only for
their compliance strategies, but also basic business decisions such as
vehicle mix, plant construction, battery development, finance, and
marketing strategies. Many manufacturers have slowed their BEV
expansion plans and shifted focus toward ICE vehicles (including HEVs).
The following summary is meant to describe changes some manufacturers
have announced to their product plans that lend support for this
proposal to extend the Tier 3 standards for MYs 2027 and 2028.\28\
---------------------------------------------------------------------------
\28\ Note that the EPA has not relied on any CBI in this
summary.
---------------------------------------------------------------------------
In June 2025, General Motors (GM) announced a $4 billion investment
in engine and vehicle production in three U.S. facilities in Michigan,
Kansas, and Tennessee as it moves to boost production of ICE vehicles
in response to slowing BEV demand.\29\ In October 2025 GM announced
that it took a $1.6 billion impairment charge to align its BEV
manufacturing capacity with consumer demand.\30\ In January 2026, GM
announced a further ``$6 billion charge to unwind some electric-vehicle
investments.'' \31\
---------------------------------------------------------------------------
\29\ See Hall, K. and Shepardson, D. (2025). ``GM to invest $4
billion in three US facilities as it ramps up gas-powered
vehicles.'' Reuters: https://www.reuters.com/business/autos-transportation/general-motors-investing-3-us-facilities-production-gas-electric-vehicles-2025-06-10/.
\30\ See Staff. (2025). ``GM announces $1.6B charge on dwindling
EV adoption,'' The Business Journal (Youngstown): https://businessjournaldaily.com/gm-announces-1-6b-charge-on-dwindling-ev-adoption/.
\31\ Staff. (2026). GM to take $6 billion writedown on EV
pullback. Reuters: https://www.reuters.com/business/autos-transportation/gm-take-6-billion-writedown-ev-pullback-2026-01-08/.
---------------------------------------------------------------------------
Ford Motor Company (Ford) has also reduced spending on BEVs and
scaled back previously announced production plans for existing BEVs and
future BEV launches. Ford cancelled plans for a three-row electric
sport utility vehicle (SUV) and delayed the launch of major platforms
such as the F-150 Lightning successor and a new E-Transit van until
2028.\32\ Ford announced a strategic pivot to hybrids citing customer
demand. In September 2025, Ford stated that the U.S. BEV market will be
``way smaller than we thought,'' projecting that the BEV market will be
cut in half after the current incentives expire. Ford also stated that
it will plan more affordable, smaller BEVs to compete with Tesla and
BYD.\33\ Ford's adjustments include battery manufacturing capacity and
in October 2025, Ford scaled back a major lithium supply deal,
reflecting the industry's more cautious outlook on BEV growth.\34\
Furthermore, in December 2025, Ford announced a $19.5 billion write-
down in its investments in BEVs.\35\
---------------------------------------------------------------------------
\32\ See Tucker, S. (2024). Ford shuffles EV plans: Canceling,
delaying big ones. Kelley Blue Book: https://www.kbb.com/car-news/ford-shuffles-ev-plans-canceling-delaying-big-ones/.
\33\ See Wayland, M. (2025). Ford CEO expects EV sales to be cut
in half after end of tax credits. CNBC: https://www.cnbc.com/2025/09/30/ford-ceo-jim-farley-ev-incentives.html.
\34\ See Bloomberg. (2025). Ford Delays Lithium Supply Deal as
EV Struggles Continue, https://www.supplychainbrain.com/articles/42643-ford-delays-lithium-supply-deal-as-ev-struggles-continue.
\35\ See Colias, M. (2025). Ford's $19.5 billion EV writedown:
Five things to know. Reuters; https://www.reuters.com/business/autos-transportation/fords-195-billion-ev-writedown-five-things-know-2025-12-16/.
---------------------------------------------------------------------------
Stellantis, which includes the Chrysler, Jeep, and RAM nameplates,
is also shifting away from BEVs.\36\ Stellantis is instead adopting
hybrid technology and emphasizing flexible vehicle platforms that can
accommodate ICE, hybrid, and electric powertrains. As part of this
shift in product, Stellantis announced that it is reviving the Hemi V8
engine for Jeep models and is cancelling the all-electric Ram 1500 REV
pickup in lieu of a range-extended hybrid version.\37\ On January 9,
2026, Stellantis announced it was scrapping its PHEV vehicle lineup
citing waning customer demand.\38\ Stellantis also announced on
February 6, 2026, that it was taking a $26.5 billion charge against its
BEV investments.\39\
---------------------------------------------------------------------------
\36\ See Reuters. (2025). Stellantis to scrap target of 100% EVs
by 2030, says Europe chief, https://www.reuters.com/business/autos-transportation/stellantis-scrap-target-100-evs-by-2030-says-europe-chief-2025-09-08/.
\37\ See Walz, E. (2025). Stellantis cancels electric RAM pickup
amid slowing EV demand. WardsAuto: https://www.wardsauto.com/news/archive-auto-stellantis-cancels-ram-1500-bev-electric-pickup-rev-extended-range/760779.
\38\ See Wayland, M. (2026). Stellantis scraps Jeep, Chrysler
plug-in hybrid vehicles amid EV slowdown, recall. https://www.cnbc.com/2026/01/09/stellantis-scraps-jeep-chrysler-phevs-amid-ev-slowdown-recall.html.
\39\ See Revell, E. (2026). Stellantis takes massive $26B hit
after moving away from EVs. Fox Business; https://www.foxbusiness.com/markets/stellantis-takes-massive-26b-hit-after-moving-away-from-evs.
---------------------------------------------------------------------------
Honda also announced the slowdown of BEV developments in the past
year, reducing its BEV spending by 30 percent and pausing a $10.7
billion Canadian BEV factory conversion for two years, citing slower-
than-anticipated BEV market expansion.\40\ Honda discontinued the Acura
ZDX BEV \41\ and cancelled plans to launch its new ``0 Series'' BEVs,
the 0 Series SUV, the 0 Series Saloon, and the Acura RSX, which would
have been built starting in 2026, citing ''Recent changes in the
business environment.'' \42\ Honda is focusing on hybrids with the
rollout of 13 new hybrid models \43\ by 2031 in addition to their
current hybrid lineup and ICE vehicles. Volkswagen is adjusting
production plans and has halted production at some German BEV plants in
response to weaker-than-anticipated demand. In September 2025, the
Volkswagen Group's chief executive officer said manufacturers were
experiencing ``massive changes'' with ``a
[[Page 28472]]
clear drop in demand for battery-electric cars.\44\
---------------------------------------------------------------------------
\40\ See Friedman, G. (2025). Honda reveals delay of $15-billion
Canada investment part of shift in EV strategy. Financial Post;
https://financialpost.com/commodities/energy/electric-vehicles/honda-cutting-ev-investment-delaying-canadian-plans.
\41\ See Banner, J. (2025). Acura Just Canceled the ZDX EV, but
the Brand's Electric Story Isn't Over. MotorTrend; https://www.motortrend.com/news/acura-just-canceled-the-acura-zdx-ev.
\42\ See Honda. (2026). Honda Cancels 0 Series EVs, Acura RSX
Just Months Before Production. https://www.roadandtrack.com/news/a70722811/honda-cancels-0-series-acura-rsx-electric-vehicles/.
\43\ See Honda. (2025). https://automobiles.honda.com/; and
Daniel Leussink. (2025). Japan's Honda to scale back on electric
vehicles, focus on hybrids. Reuters; https://www.reuters.com/business/autos-transportation/japans-honda-scale-back-electric-vehicles-concentrate-hybrids-2025-05-20/.
\44\ See O'Carroll, L. (2025). VW to pause production at two
plants as electric vehicle sales stall. The Guardian; https://www.theguardian.com/business/2025/sep/26/vw-to-pause-production-at-two-plants-as-electric-vehicle-sales-stall.
---------------------------------------------------------------------------
Hyundai announced a significant increase in hybrid models from the
five models available now to over 18 hybrid models by 2030.\45\ Hyundai
halted production of the Genesis Electrified GV70 BEV in Alabama to
shift focus toward more popular and profitable hybrid SUVs like the
Tucson. Hyundai recently announced significant changes in production
plans in the U.S. and globally.\46\
---------------------------------------------------------------------------
\45\ See Hyundai Motor Company. (2025). Hyundai Motor Company
Unveils Bold 2030 Vision and Product Roadmap at 2025 CEO Investor
Day, https://www.hyundai.com/worldwide/en/newsroom/detail/hyundai-motor-company-unveils-bold-2030-vision-and-product-roadmap-at-2025-ceo-investor-day-0000001018; and Hyundai Motor Company. (2025).
Hybrid Vehicles [verbar] Hybrid Model Lineup [verbar] Hyundai USA,
https://www.hyundaiusa.com/us/en/electrified/hybrids.
\46\ See Johnson, P. (2025). Hyundai halts production of another
luxury EV. Electrek: https://electrek.co/2025/08/19/hyundai-halts-production-of-another-luxury-ev/.
---------------------------------------------------------------------------
The changes to BEV product plans summarized above are likely to
significantly impact manufacturers' ability to comply with the Tier 4
standards. Vehicle manufacturers have the option to demonstrate
compliance with the phase-in requirements using a mix of ICE vehicles,
HEVs, PHEVs, and BEVs. Manufacturers planning to rely on BEV sales for
their Tier 4 compliance plans have likely seen those plans change
significantly in just the past year.
As discussed in the LMDV Multipollutant Rule, many manufacturers
publicly reported significant projected near and long-term growth in
BEVs and PHEVs in 2023 and 2024. In response to these manufacturer
announcements and investments in these technologies and supporting
infrastructure made by Congress, numerous third-parties, as well as the
EPA, also projected significant growth of BEV and PHEV adoption, which
the Agency considered and relied upon when developing and finalizing
the LMDV Multipollutant Rule.\47\ The EPA is revisiting these
projections and the Tier 4 program in response to the many changes in
Federal and State policies, Federal legislation, and Federal and State
regulatory requirements that have occurred since the LMDV
Multipollutant Rule was finalized in April 2024, as well as the actual
consumer interest in purchasing BEVs. As discussed earlier, this Part 1
rule proposes to extend the Tier 3 program by two additional MYs due to
feasibility concerns. In the future Part 2 rule, EPA will
comprehensively reconsider the Tier 4 program for light- and medium-
duty vehicles, which may include, for example, changes to the Tier 4
emission standards, lead time and phase-in schedule, and test
procedures.
---------------------------------------------------------------------------
\47\ See ``Multi-Pollutant Emissions Standards for Model Years
2027 and Later Light-Duty and Medium-Duty Vehicles,'' 88 FR 29184
(May 5, 2023), Sections I.A.ii and I.A.iii at 29187-29196; and LMDV
Multipollutant Rule, Sections I.A.2 and I.A.3 at 27845-27853.
---------------------------------------------------------------------------
C. Automotive Vehicle Development Cycle Lead Time Considerations
Typical automobile development cycles run approximately four to
five years, starting with initial concepts and continuing through
vehicle prototypes, production tooling, and large-volume
industrialization across a company's product lines. The time needed to
conceive, create, and deliver a new vehicle to market can be two and a
half years or more.\48\ Changes in existing vehicle platforms can vary
from one year for a mid-cycle refresh to more than two years for a
full-scale vehicle redesign. In addition, vehicle manufacturers often
comply with incremental changes in EPA emission standards in a
``surgical'' manner, with only marginal headroom built into production
capacity to cover sales fluctuations.
---------------------------------------------------------------------------
\48\ See Center for Automotive Research. (2007). How Automakers
Plan Their Products, https://www.cargroup.org/wp-content/uploads/2017/02/HOW-AUTOMAKERS-PLAN-THEIR-PRODUCTS.pdf.
---------------------------------------------------------------------------
Manufacturers may respond to the changing conditions in several
ways, with each option having a different lead time. Examples include
changing the price of their BEVs--those not canceled or delayed--to
compensate for lost purchasing and leasing tax incentives, restricting
production of some ICE vehicles that do not support Tier 4 compliance,
or developing additional ICE vehicles with the requisite technology to
support Tier 4 compliance. The first two options--changing pricing and
restricting ICE vehicle products--still may not result in a company
being able to demonstrate compliance with the MYs 2027 and 2028 Tier 4
standards. Furthermore, they may have potentially significant near-term
financial impacts on manufacturers and potentially negatively impact
consumers through reduced choices of vehicle models. For these reasons,
the EPA does not believe these two options are feasible for all
manufacturers. The third option, developing additional improved ICE
vehicles on short notice to meet the current Tier 4 phase-in
requirements for MYs 2027 and 2028, is likely infeasible because there
is not sufficient lead time for firms to make such changes.
D. Expected Manufacturer Response With Lower BEV Projections
In light of the change in the BEV landscape, the EPA now expects
manufacturers would consider improvements to ICE vehicle technologies
as a means to comply with the Tier 4 criteria pollutant program. This
could include technology plans that require improvements in gasoline
ICE vehicle exhaust aftertreatment systems, engine controls, and
monitoring systems in several significant ways-approaches which require
a change in companies' technology development plans which requires lead
time. These improved systems include better three-way catalytic
converters (TWCs) to reduce NMOG+NOX emissions; the addition
of GPFs to reduce PM emissions; and related electrical systems,
software, and calibrations required to operate the modified and added
hardware. In addition, new components and systems, such as GPFs, must
be integrated into the vehicle exhaust aftertreatment system and may
require changes to vehicle design and packaging, as well as changes to
manufacturing production lines to install these components. Vehicle
onboard diagnostics (OBD) that support the Tier 4 standards will also
require additional development and calibration, with the OBD associated
with the implementation of GPFs potentially representing a new
requirement for manufacturers. Exhaust and aftertreatment components,
such as catalysts, sensors, and GPFs, that are required to support more
stringent standards are typically produced by automotive suppliers,
with their own set of planning and production requirements and
associated lead times. Finally, vehicle manufacturers are also expected
to improve their emissions test capabilities to ensure continued
accurate measurement of PM emissions and the addition of cold ambient
temperature PM testing. These actions normally require several years to
accomplish.
Given the policy, legislative, regulatory, and marketplace changes
which have occurred, the start of MY 2027, and the upcoming start of MY
2028, the EPA does not believe the automotive industry and supplier
base have adequate lead time to revise their product plans to develop
and industrialize the requisite ICE vehicle technology to support the
near-term Tier 4 phase-in. The EPA believes that many
[[Page 28473]]
manufacturers planned on high BEV sales to comply with the Tier 4
requirements and did not plan for the alternative, which is
implementing changes, as described above, to large portions of their
ICE product line. Manufacturers would need to revise plans, source
suppliers, and make necessary changes to assembly lines to implement
the updates needed in their ICE vehicles--but there is insufficient
time to complete those steps for MYs 2027 and 2028. The EPA proposes
that, at minimum, a two-year extension of the Tier 3 program is needed
to ensure companies can comply with the Agency's emission standards.
While some companies have certified Tier 4 vehicles for MY 2027, the
product mix and sales volume for MY 2027 are unknown and thus the
impacts on NMOG+NOX fleet averages are unknown. No
manufacturers have yet certified MY 2028 products. Based on the
previous discussion on manufacturer product cycle development, the EPA
proposes an initial two-year extension of the Tier 3 program in this
Part 1 Tier 4 reconsideration rule. The EPA will continue to evaluate
manufacturers' progress and the comments the Agency receives in
response to this proposal to determine whether an additional extension
of Tier 3 may become necessary (e.g., an extension to MY 2029). The
issues the EPA discusses above with respect to the significant changes
in the BEV landscape since the Agency issued the Tier 4 final rule in
April 2024 extend beyond MYs 2027 and 2028. In the future Part 2 rule,
the EPA will comprehensively reconsider the Tier 4 program for light-
and medium-duty vehicles for future MYs beyond those addressed in this
Part 1 rule. Changes to the Tier 4 program may include changes to
elements such as the Tier 4 emission standards, lead time and phase-in
schedule, and test procedures.
The recent changes in policy, regulations, Federal law, and near-
term BEV market share projections have disrupted vehicle manufacturers'
near-term product plans. BEVs were a major factor contributing to Tier
4 program compliance, both for the per-vehicle standards such as PM and
for NMOG+NOX fleet averaging standard. A lower projected BEV
market share makes compliance with the Tier 4 standards challenging and
perhaps unachievable. Therefore, the EPA is reconsidering the Tier 4
program. In this Part 1 rule proposal, the EPA is proposing to extend
the Tier 3 standards through MYs 2027 and 2028 for light- and medium-
duty vehicles due to feasibility concerns. This proposal is consistent
with the EPA's responsibilities and authority under CAA sections 202(a)
and (b). The EPA carefully considered the statutory factors, including
technological feasibility, cost, and lead time for manufacturers to
comply with the standards.\49\ The two-year extension of the Tier 3
standards would result in a very small foregone reduction in emissions
of criteria pollutants and air toxics and will represent significant
cost savings for vehicle manufacturers in MYs 2027 and 2028 as
discussed in section III.B of this preamble and Chapter 1 of the DRIA
for this proposed rule.\50\ Notably, the Tier 3 standards themselves
represent a significant reduction in criteria pollutant emissions, and
the MY 2025 and later standards that the Agency is proposing to extend
to MYs 2027 and 2028 are the most stringent of the Tier 3 standards.
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\49\ 42 U.S.C. 7521(a).
\50\ U.S. Environmental Protection Agency, Revision of Tier 4
Phase-In Schedule for Light-Duty and Medium-Duty Vehicles: Draft
Regulatory Impact Analysis (Apr. 2026) EPA Technical Report EPA-420-
D-26-001 (``DRIA'').
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E. What is the EPA proposing to change?
The EPA is proposing to extend the existing Tier 3 standards for
light- and medium-duty vehicles through MYs 2027 and 2028. This
proposed change, which is summarized in Tables 8 and 9, extends Tier 3
requirements to MYs 2027 and 2028 and then, in MY 2029, resumes the
phase-in schedule for the Tier 4 requirements described in section II.A
of this preamble, including the per-vehicle PM, CO, and HCHO standards.
Tables 8 and 9 show the fraction of vehicles that will need to meet the
Tier 3 or final Tier 4 standards. For example, ``0% Tier 4'' means that
there is no minimum fraction of vehicles in a MY that must comply with
all aspects of the Tier 4 program; rather, all vehicles sold can
partially comply as interim Tier 4 vehicles. Likewise, ``60% Tier 4''
means that 60 percent of the vehicles sold must be certified to final
Tier 4 standards and the remainder may be interim or final Tier 4.
Additionally, the proposed early schedules for heavier light- and
medium-duty vehicles (see Tables 8 and 9, respectively) are intended to
maintain alignment with the proposed phase-in schedule for vehicles up
to 6,000 pounds GVWR. The reasons for this proposal are described in
detail in section II.B of this preamble.
Table 8--Proposed Amended Tier 4 Light-Duty Program Vehicle Criteria Pollutant Phase-In Schedules
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vehicle GVWR <= 6000 lb Vehicle GVWR 6001-8500 lb and MDPV
Model year -----------------------------------------------------------------------------------------------------------------------
Current Proposed Current default Current early Proposed default Proposed early
--------------------------------------------------------------------------------------------------------------------------------------------------------
2027............................ 20% Tier 4........ 100% Tier 3....... 0% Tier 4......... 20% Tier 4........ 100% Tier 3....... 100% Tier 3.
2028............................ 40% Tier 4........ 100% Tier 3....... 0% Tier 4......... 40% Tier 4........ 100% Tier 3....... 100% Tier 3.
2029\a\......................... 60% Tier 4........ 60% Tier 4........ 0% Tier 4......... 60% Tier 4........ 0% Tier 4......... 60% Tier 4.
2030............................ 100% Tier 4....... 100% Tier 4....... 100% Tier 4....... 100% Tier 4....... 100% Tier 4....... 100% Tier 4.
2031............................ 100% Tier 4....... 100% Tier 4....... 100% Tier 4....... 100% Tier 4....... 100% Tier 4....... 100% Tier 4.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Vehicles not yet meeting all Tier 4 requirements will certify as Interim Tier 4 vehicles using the Tier 3 standards.
Table 9--Proposed Amended Tier 4 Medium-Duty Vehicle Criteria Pollutant Phase-In Schedules
----------------------------------------------------------------------------------------------------------------
MDV\a\ (GVWR 8501-14000 lb)
Model year -------------------------------------------------------------------------------
Current Default Current Early Proposed Default Proposed Early
----------------------------------------------------------------------------------------------------------------
2027............................ 0% Tier 4......... 20% Tier 4........ 100% Tier 3....... 100% Tier 3.
2028............................ 0% Tier 4......... 40% Tier 4........ 100% Tier 3....... 100% Tier 3.
2029\b\......................... 0% Tier 4......... 60% Tier 4........ 0% Tier 4......... 60% Tier 4.
[[Page 28474]]
2030............................ 0% Tier 4......... 80% Tier 4........ 0% Tier 4......... 80% Tier 4.
2031............................ 100% Tier 4....... 100% Tier 4....... 100% Tier 4....... 100% Tier 4.
----------------------------------------------------------------------------------------------------------------
\a\ MDV refers to medium-duty vehicle, which is a combination of both Class 2b and 3 vehicles as defined in 40
CFR 86.1803-01.
\b\ Vehicles not yet meeting all Tier 4 requirements will certify as Interim Tier 4 vehicles using the Tier 3
standards.
This proposed action would also extend the Tier 3
NMOG+NOX fleet average standards for light-duty program
vehicles up to 6,000 pounds GVWR through MYs 2027 and 2028. Then, in MY
2029, the Tier 4 sales-weighted fleet average standards schedule for
NMOG+NOX would resume, as shown in Table 10. All other
elements of the Tier 4 program, such as the changes in required drive
cycles for certification and the NMOG+NOX altitude
standards, are also proposed to be delayed to MY 2029.
Table 10--Proposed Light-Duty Program Vehicle Fleet Average NMOG+NOX Standards
----------------------------------------------------------------------------------------------------------------
LDV, LDT1-2 (GVWR LDT3-4 (GVWR 6001-8500 lb) and MDPV NMOG+NOX (mg/
<=6000 lb) NMOG+NOX (mg/ mi.)
Model year mi.) -------------------------------------------------
-------------------------
Proposed Default Proposed early
----------------------------------------------------------------------------------------------------------------
2026\ a\............................. \a\ 30 \ a\ 30 \ a\ 30
2027................................. 30 30 30
2028................................. 30 30 30
2029................................. 21 30 21
2030................................. 19 15 19
2031................................. 17 15 17
2032 and later....................... 15 15 15
----------------------------------------------------------------------------------------------------------------
\a\Tier 3 standards provided for reference.
The LMDV Multipollutant Rule central analysis case projections for
BEV market share in MYs 2027 and 2028 were 26 and 31 percent,
respectively, across all light-duty program vehicles.\51\ For this
proposed action, the EPA projects the BEV market share to be eight and
12 percent in MYs 2027 and 2028, respectively.\52\ This projection
means that BEVs will have a market share in MY 2027 that is 18
percentage points lower than previously estimated in the LMDV
Multipollutant Rule, and in MY 2028, 19 percentage points lower.
Likewise, the BEV share of MDVs is projected to be reduced to one
percent from three and four percent in MYs 2027 and 2028, respectively.
BEVs have a significant impact on manufacturers' compliance because of
their zero mg/mile certification values. The changes in regulatory and
market conditions described in section II.B of this preamble are
expected to result in lower projected BEV market share and disrupt
manufacturers' compliance strategies. This proposed action would
provide manufacturers with additional lead time to comply in
recognition of the issues described in section II.C of this preamble.
---------------------------------------------------------------------------
\51\ See Table 3 of LMDV Multipollutant Rule at 89 FR 27856.
\52\ See U.S. Environmental Protection Agency. (2026). ``Battery
Electric Vehicle Projected Market Share Analysis.'' EPA-HQ-OAR-2025-
3297.
---------------------------------------------------------------------------
In addition, the EPA is proposing some clarifications to the
regulatory language regarding requirements in 40 CFR parts 85, 86, and
1066. For example, the EPA is proposing to revise 40 CFR
1066.801(c)(1)(i) and 40 CFR 1066.815(a)-(c) to clarify that a
manufacturer may use the hot-running portion of the urban dynamometer
driving schedule (UDDS) from the cold-start UDDS or the hot-start UDDS
in the FTP composite emission calculations in 40 CFR 1066.820(b) and
(c)(1), if the manufacturer chooses to run a full hot-start UDDS for
the purposes of measuring PM with a non-hybrid ICE vehicle consistent
with 40 CFR 1066.815(b)(5). This option is available for non-hybrid ICE
vehicles when testing on the FTP at either 25 [deg]C or -7 [deg]C
ambient temperature conditions. In addition, HEVs may use the full hot-
start UDDS or only the first 505 sections thereof for the purposes of
measuring PM from HEVs on the FTP at -7 [deg]C ambient temperature.
Note that this clarification does not substantively alter testing
obligations.
F. The EPA's Clean Air Act Authority for This Proposal
The EPA's statutory authority for this proposed action is found in
CAA section 202(a)(1)-(2).\53\ CAA section 202(a)(1) requires the
Administrator to ``prescribe (and from time to time revise) . . .
standards applicable to the emission of any air pollutant from any
class or classes of new motor vehicles or new motor vehicle engines,
which in his judgement cause, or contribute to, air pollution which may
reasonably be anticipated to endanger public health or welfare,'' and
CAA section 202(a)(2) requires the Administrator to determine the
necessary time ``to permit the development and application of the
requisite technology, giving appropriate consideration to the cost of
compliance within such period'' before such standard or revision shall
go into effect.
---------------------------------------------------------------------------
\53\ 42 U.S.C. 7521(a)(1)-(2).
---------------------------------------------------------------------------
In this proposed action, the EPA is amending the phase-in schedule
for the Tier 4 standards for MYs 2027 and 2028 by extending the Tier 3
standards, consistent with the authority granted to the Agency by CAA
section 202. CAA section 202 directs the EPA to give appropriate
consideration to the cost and lead time necessary to allow for the
[[Page 28475]]
development and application of such technology required for compliance
with the standards. In determining the level of the standards, CAA
section 202(a) does not specify how much weight to apply to each
factor. Thus, the EPA may determine an appropriate balance between
stringency, technology considerations, cost, and lead time.\54\ Unless
provided otherwise by statute, an agency may revise or rescind prior
actions so long as it acknowledges the change in position, provides a
reasonable explanation for the new position, and considers legitimate
reliance interests in the prior position.\55\
---------------------------------------------------------------------------
\54\ See Sierra Club v. EPA, 325 F.3d 374, 378 (D.C. Cir. 2003)
(even where a provision is technology-forcing, the provision ``does
not resolve how the Administrator should weigh all [the statutory]
factors''); Nat'l Petrochemical and Refiners Ass'n v. EPA, 287 F.3d
1130, 1135 (D.C. Cir. 2002) (EPA decisions, under CAA provision
authorizing technology-forcing standards, based on complex
scientific or technical analysis are accorded particularly great
deference); see also Husqvarna AB v. EPA, 254 F. 3d 195, 200. (D.C.
Cir. 2001) (great discretion to balance statutory factors in
considering level of technology-based standard, and statutory
requirement ``to [give appropriate] consideration to the cost of
applying . . . technology'' does not mandate a specific method of
cost analysis); Hercules Inc. v. EPA, 598 F. 2d 91, 106 (D.C. Cir.
1978) (``In reviewing a numerical standard we must ask whether the
agency's numbers are within a zone of reasonableness, not whether
its numbers are precisely right.'').
\55\ See FDA v. Wages & White Lion Invs., L.L.C., 604 U.S. 542
(2025); FCC v. Fox Television Stations, Inc., 556 U.S. 502 (2009);
Motor Vehicle Mfrs. Ass'n v. State Farm Mut. Auto. Ins. Co., 463
U.S. 29 (1983); Clean Air Council v. Pruitt, 862 F.3d 1, 8 (D.C.
Cir. 2017) (``Agencies obviously have broad discretion to reconsider
regulations at any time'').
---------------------------------------------------------------------------
G. Reliance Interests
The EPA understands that companies have previously planned for the
MY 2027 start date for Tier 4 criteria pollutant standards, especially
with respect to the PM standards, and some have already expended
resources, including through research and development, complying with
the MYs 2027 and 2028 standards. As stated above, significant changes
have occurred due to Federal and State policy changes, as well as
consumer preferences, and companies have responded by modifying their
product lines. The EPA acknowledges that this proposal would, if
finalized, change the Agency's previous assessments in the 2024 Tier 4
Rule with respect to the feasibility or the Tier 4 implementation
schedule and the appropriateness of concluding the Tier 3 program on
the timetable then envisioned. However, as explained throughout this
preamble, the EPA believes this change in position is necessary and
supported by intervening developments that impact the analyses and
assumptions used in the 2024 Tier 4 Rule and manufacturers' initial
compliance planning in response thereto.
The EPA believes that the revisions proposed in this action relieve
obligations in a manner that promotes compliance and costs savings
without undermining existing investments in compliance. Specifically,
the EPA seeks comment on whether regulated parties have any significant
reliance interests with respect to MYs 2027 and 2028 Tier 4 criteria
pollutant standards only, as GHG standards or post-MY 2029 impacts are
outside the scope of this rule. The EPA is aware that manufacturers,
importers, and sellers have already expended resources complying with
Tier 4 criteria pollutant standards for MYs 2027 and 2028, because many
compliance costs are incurred as part of research and development and
during manufacturing. However, given the statutory obligation to
consider these lead time concerns in light of the dramatically changed
landscape discussed throughout this notice, the EPA does not believe
reliance interests in the timing of the Tier 4 standards, if any exist
at this point, outweigh the need to reconsider the Tier 4 program as
proposed here.
Nevertheless, the EPA seeks comment on whether regulated parties
have any significant reliance interests with respect to MYs 2027 and
2028 Tier 4 criteria pollutant standards that are not already
considered in this rulemaking that should be considered, and on how
such interests should be considered. Note that MY 2029 impacts are
beyond the scope of this rule except where explicitly noted, and that
former GHG standards are not at issue in this proposal.
The EPA further understands that other interested parties may have
relied on the MY 2027 start date for Tier 4 criteria pollutant
standards for independent purposes, including compliance with relevant
National Ambient Air Quality Standards (NAAQS) and related planning
obligations, among others. For example, the EPA understands that, by
resulting in marginally increased emissions, the proposed rule could
conceivably have implications for State departments of transportation
and metropolitan planning organizations that factored prior emission
pollution projections into their planning processes for the purposes
of, among other things, obtaining of Federal transportation funding.
The EPA believes that the relatively small nature of the foregone
emissions reductions involved in this proposed revision, coupled with
the relatively short amount of time that has passed since promulgation
of the 2024 Tier 4 Rule, means that such interests do not supersede the
Agency's obligation to ensure that standards are feasible and
appropriately reflect technical and market realities. Moreover, the EPA
notes that mobile-source standards are just one consideration among
many involved in planning to attain the NAAQS and related obligations.
Nevertheless, the EPA seeks comment on such reliance interests and how
such interests should be taken into account in any final action on this
proposal.
The EPA seeks comment on the nature and extent of any other
reliance interests that may arise from this proposed action and is
committed to assessing any such interests, determining whether they are
significant, and weighing such interests against competing rationales,
as required by law.\56\
---------------------------------------------------------------------------
\56\ See, e.g., DHS v. Regents of Univ. of Cal., 591 U.S. 1, 33
(2020).
---------------------------------------------------------------------------
III. What are the projected impacts of this proposed rule?
In this section of the preamble, the EPA presents a summary of the
findings that are presented in detail in the DRIA for this proposed
rule. This includes a description of the approach the EPA used to
evaluate the impacts of this proposed rule on compliance costs,
emissions, air quality, and human health. The EPA also presents a
summary of the proposed action's projected impacts on the costs of
compliance, which for this proposal is a cost savings for the
automotive manufacturers.
A. What approach did the EPA use in analyzing this proposal?
Projecting BEV market share is an important component of the EPA's
cost and emissions impact analysis. The EPA recognizes that
manufacturers could use BEVs to meet the existing Tier 4 standards for
MYs 2027 and 2028 to the extent practicable, with the remaining
compliance obligations coming from emissions improvements to ICE
vehicles. The EPA projects the expected level of BEV market share to be
eight percent in MY 2027 and 12 percent in MY 2028. It is also
consistent with sales figures over the last two to three years.\57\
Third-party BEV market share projections in MYs 2027 and 2028 are
dynamic and show a wide range of potential adoption. Bloomberg New
Energy Finance originally forecast in
[[Page 28476]]
2024 that 48 percent of passenger sales in the U.S. would be BEVs in
2030 but in 2025 revised that down to 27 percent.\58\ In February 2025,
J.D. Power projected BEV sales of 15.2 and 18.3 percent, respectively
in 2027 and 2028.\59\ According to AutoPacific's most recent forecast,
BEV market share in the U.S. is expected to remain at eight percent in
2026, the same as it was in 2025. This represents a decrease from
AutoPacific's 2024 estimate, when it predicted market share would reach
15 percent in 2026.\60\ According to CNN reporting, while 10 percent of
all cars sold in the U.S. in the third quarter of 2025 were electric,
Ford Chief Executive Officer Jim Farley said in September 2025 that he
expects BEV sales to fall from seven percent of the U.S. market in 2025
to five percent in 2026.\61\ GM Chief Financial Officer Paul Jacobson
said that his company also expects that ``EV demand is going to drop
off pretty precipitously.'' \62\ The EPA believes the estimates of
eight and 12 percent BEV market share are consistent with these other
projections and are therefore a reasonable basis for estimating the
costs and emissions impacts associated with this proposed action.
---------------------------------------------------------------------------
\57\ Alliance for Automotive Innovation. (2025). Reading the
Meter.'' https://www.autosinnovate.org/posts/papers-reports/ReadingtheMeter9-5-2025.pdf.
\58\ McKerracher, C. et al. (2025). Electric Vehicle Outlook
2025. BloombergNEF: https://about.bnef.com/insights/clean-transport/electric-vehicle-outlook/.
\59\ J.D. Power. (2025). 2025 to be reset year for EV sales,
https://www.jdpower.com/business/resources/e-vision-intelligence-report-january-2025.
\60\ Gearino, D. (2025). ``What's Ahead for the US Electric
Vehicle Industry After Hitting a Massive Speed Bump?'' https://insideclimatenews.org/news/09102025/inside-clean-energy-us-ev-industry-future/.
\61\ Isidore, C. (2025). ``The future for EVs in America looks
grim. But the auto industry isn't giving up.'' https://www.cnn.com/2025/10/06/business/automakers-ev-plans.
\62\ Id.
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The EPA evaluated a no-action case and an action case for this
proposal. The EPA's no-action case assumes that the Tier 4 phase-in
stays as introduced in the LMDV Multipollutant Rule. The action case is
the proposed extension of Tier 3 requirements for MYs 2027 and 2028 as
described in section II.C of this preamble.
The current Tier 3 program requires that manufacturers meet a 30
mg/mile NMOG+NOX fleet average standard. Vehicle
manufacturers are complying with the current Tier 3 program using a
variety of technologies, including BEVs. In the LMDV Multipollutant
Rule, the EPA projected that manufacturers could adopt a variety of
technologies to comply with the Tier 4 program, and, when evaluated in
combination with the GHG standards established in the LMDV
Multipollutant Rule and other factors in that analysis, projected that
the sales of additional BEVs would be the most cost-effective means of
meeting the multipollutant standards. In consideration of the changing
BEV landscape discussed in section II.B of this preamble, the EPA
modeled compliance with the Tier 3 and Tier 4 programs using ICE
emission control technologies as needed to project compliance after
accounting for a more realistic share of BEVs into the fleet average.
The EPA recognizes that this is one of numerous pathways to
compliance--for example, manufacturers could instead rely on more or
fewer BEVs than assumed here--and consequently there is some
uncertainty in the projected changes in costs.
There are likely to be sources of uncertainty in any complex
analysis using estimated parameters and inputs from numerous models and
assumptions. These uncertainties may impact both the baseline and the
post-rule analysis, thus possibly affecting the estimated incremental
impacts of the proposed rulemaking. In this analysis, the EPA
considered several sources of uncertainty, both quantitatively and
qualitatively, related to the costs and benefits of this action. More
information on uncertainty related to costs, including estimates of BEV
market share and variations in catalyst precious metal loading in TWCs,
can be found in section III.B of this preamble and Chapter 1 of the
DRIA for this proposed rule. More information on uncertainty related to
benefits, including the quantification of health and welfare effects,
can be found in section III.E of this preamble and Chapter 3 of the
DRIA for this proposed rule.
B. What are the projected changes in costs?
The EPA's cost analysis considers the incremental changes in costs
to manufacturers associated with NMOG+NOX and PM controls on
vehicles sold in MYs 2027 and 2028. These costs are calculated on an
industry-wide basis. This proposal would extend by two years the
existing Tier 3 program for vehicles less than 6,000 pounds GVWR. As a
result of the proposed changes discussed in section II.B of this
preamble, this proposal would lead to cost savings for the action case
compared to the costs projected for the no-action case.
The full analysis is presented in Chapter 1 of the DRIA that
accompanies this preamble. In this proposal, the EPA estimates cost
savings from changing NMOG+NOX control technology and PM
control technology for MYs 2027 and 2028. The per-vehicle savings are
calculated separately for the NMOG+NOX control technology
and PM control technology because they are applied to different numbers
of vehicles in each MY. The per-vehicle savings for NMOG+NOX
control technology are estimated to be about $59 with a three percent
discount rate and $56 with a seven percent discount rate. These savings
are projected to apply to 9.38 million vehicles in 2027 and 8.97
million vehicles in 2028. The per-vehicle savings for PM control
technology are estimated to be about $171 with a three percent discount
rate and $162 with a seven percent discount rate. These savings are
projected to apply to 1.22 million vehicles in 2027 and 2.85 million
vehicles in 2028.
In total, for the central action case the EPA estimates compliance
cost savings of $1.77 billion using a three percent discount rate and
$1.66 billion using a seven percent discount rate (2024 dollars), as
summarized in Table 11. The details of this analysis are presented in
Chapter 1 of the DRIA for this proposed rule. The DRIA includes a
discussion of uncertainties in the cost analysis, including estimates
of BEV market share and variations in catalyst precious metal loading,
and also includes sensitivity analysis.\63\
---------------------------------------------------------------------------
\63\ See also section III.A of this preamble.
Table 11--Estimated Emissions Control System Cost Savings
[millions 2024$]
----------------------------------------------------------------------------------------------------------------
Cost savings
Calendar year -------------------------------------------------
3% Discount rate 7% Discount rate
----------------------------------------------------------------------------------------------------------------
2027.......................................................... $670 $640
2028.......................................................... 1,100 1,020
[[Page 28477]]
Present Value................................................. 1,770 1,660
----------------------------------------------------------------------------------------------------------------
Note: The EPA notes there are uncertainties associated with these cost savings projections. See section III.A of
this preamble and Chapter 1 of the DRIA for this proposed rule for a discussion of uncertainties.
The EPA acknowledges that there are many ways that manufacturers
could comply with the NMOG+NOX standards, including using
the Tier 4 Averaging, Banking, and Trading (ABT) provisions. Due to the
myriad potential permutations attached to the ABT program, the EPA is
presenting here only one cost case. However, the NMOG+NOX
standards allow ABT, which has the potential to reduce compliance costs
for a given manufacturer by spreading the introduction of new
technologies over multiple MYs.
The EPA also understands that, as discussed above, due to the
inability for some companies to comply with the MYs 2027 and 2028
standards, the Agency expects there is likely to be significant
additional costs related to noncompliance with the regulations stemming
primarily from product planning disruptions such as manufacturing
volume constraints and revised marketing campaigns. However, the EPA
did not attempt to monetize those impacts.
Additionally, the EPA believes that, under the current MYs 2027 and
2028 standards, there is the potential that companies would no longer
be able to provide certain vehicle models, which would result in
customers being required to purchase alternative models which may
compromise their ideal choice. The EPA requests comment on the economic
impacts of potential noncompliance with MYs 2027 and 2028 standards and
companies being forced to remove some vehicle models from the market.
C. What are the projected changes in emissions?
The emissions impacts of this proposed rule were estimated using a
regulatory version of the EPA's Motor Vehicle Emission Simulator
(MOVES5). All emission inventories were modeled using the MOVES
national domain, which includes all 50 states and the District of
Columbia but no U.S. territories. Details on emissions modeling and
inventory results, including sensitivity analyses, are presented in
Chapter 2 of the DRIA for this proposed rule.
For this proposal, both the action and no-action cases that the EPA
analyzed project that BEVs will make up eight and 12 percent of sales
of light-duty program vehicles up to 6,000 pounds GVWR in MYs 2027 and
2028, respectively. Changes in emissions between these two cases are
expected to come from changes to emissions control technologies on ICE
vehicles.
The main effects of this proposal on emissions relative to the Tier
4 baseline in the future could be small increases in volatile organic
compounds (VOC), NOX, PM, and toxics emissions. The small
increases in VOC, NOX, and gaseous air toxics result from
holding the NMOG+NOX fleet average standard at the 30 mg/
mile Tier 3 standard for two additional MYs. The small increases in PM
result from MYs 2027 and 2028 vehicles not being required to meet the
Tier 4 per-vehicle PM standards. Table 12 presents the modeled changes
in the national onroad emissions inventory for NOX, PM, VOC,
and HCHO for calendar years (CYs) 2027, 2028, 2035, 2045, and 2055,
including percent changes in those years. Positive values for emissions
changes reflect emissions increases. The estimated impact of the
proposed rule on VOC is equal to or less than a 0.1 percent increase in
the total onroad vehicle emissions in the years presented. Increases in
NOX are equal to or less than 0.2 percent, while onroad
PM2.5 emissions increases range between 0.2 and 1.6 percent
for the years presented. The DRIA includes additional detail on these
projected changes, as well as projected changes in emissions for
several air toxics emissions.
Similar to the cost savings estimates, the extent that
manufacturers use ABT in their compliance strategies could have
emissions implications. For example, an original equipment manufacturer
(OEM) overcomplying with the standards in MY 2027 could reduce
emissions in CY 2027 and subsequently increase emissions in later years
as the OEM uses the banked credits.
---------------------------------------------------------------------------
\64\ Sulfur dioxide (SO2) and CO emissions do not
change with this proposed rule.
\65\ PM2.5 changes only come from tailpipe emissions.
Brake wear and tire wear emissions are not changing with this
proposed rule.
Table 12--Annual Increases in National Onroad Emissions From This Proposal for Select Calendar Years
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
CY 2027 CY 2028 CY 2035 CY 2045 CY 2055
---------------------------------------------------------------------------------------------------------------------------------
Pollutant \64\ Percent Percent Percent Percent Percent
U.S. tons onroad U.S. tons onroad U.S. tons onroad U.S. tons onroad U.S. tons onroad
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Nitrogen Oxides (NOX)......................................... 389 <0.1 976 0.1 1031 0.2 482 0.1 106 <0.1
Particulate Matter \65\ (PM2.5)............................... 51 0.2 145 0.5 167 1.1 102 1.6 27 0.7
Volatile Organic Compounds (VOC).............................. 353 <0.1 859 0.1 878 0.1 405 0.1 92 <0.1
Formaldehyde.................................................. 4 0.1 9 0.2 10 0.3 5 0.2 1 <0.1
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
[[Page 28478]]
D. What are the projected changes in air quality?
Section III.C of this preamble presents projections of the
emissions changes due to this proposed rule. For this proposal, the EPA
did not conduct air quality modeling to determine how these emissions
increases could change the ambient concentrations of air pollutants.
Making predictions about air quality based solely on emissions changes
is extremely difficult because the atmospheric chemistry related to
ambient concentrations of PM, ozone, and air toxics is very complex,
and the emissions changes are spatially variable. Nevertheless,
considering the air quality modeling conducted for recent vehicle rules
and the relatively small projected increase in total onroad emissions
from this proposal, overall, the EPA expects relatively small changes
in ambient concentrations of air pollutants from this proposal.\66\
---------------------------------------------------------------------------
\66\ See LMDV Multipollutant Rule and ``Control of Air Pollution
from New Motor Vehicles: Heavy-Duty Engine and Vehicle Standards,''
88 FR 4296-4718 (Jan. 24, 2023).
---------------------------------------------------------------------------
E. What are the projected changes in human health and welfare?
Air pollutants emitted from motor vehicles impact public health,
welfare, and the environment. Motor vehicle emissions contribute to
ozone, PM2.5, and air toxics, which are linked to premature
death and other serious health impacts, including respiratory illness,
cardiovascular problems, and cancer. This air pollution affects people
nationwide, especially those who live or work near transportation
corridors. Detailed information on the health and welfare effects
associated with exposure to pollutants impacted by this proposed rule
can be found in sections II.B-D of the LMDV Multipollutant Rule's
preamble and Chapter 6 of the LMDV RIA.\67\
---------------------------------------------------------------------------
\67\ See LMDV Multipollutant Rule and LMDV RIA.
---------------------------------------------------------------------------
The EPA sometimes performs air quality modeling to conduct a full
assessment of the PM2.5-related and ozone-related human
health benefits of the Agency's regulatory actions. As discussed in
section III.D of this preamble, the EPA did not conduct air quality
modeling for this proposal.
The EPA is obligated to present the Agency's best scientific
understanding and the implications of that science when developing
policies and regulations. However, historically, the EPA's analytical
practices may not have presented the full range of uncertainties and
associated confidence level regarding the potential benefit estimates
from reduction in exposure to PM2.5 and ozone. In addition,
the science regarding the exposure, health effects from exposure, and
valuation of reduction in health effects are evolving with better data
and methods, especially at low concentrations of PM and ozone. The
EPA's use of benefit per ton (BPT) monetized values introduces
additional uncertainty. Although developed as a screening tool when
full-form photochemical modeling was not feasible, the BPT approach
reduces complex spatial and atmospheric relationships and may be more
suited to model emissions that are geographically more uniform and the
pollutant species are better mixed, thereby adding uncertainty
associated with those estimates. Some of the sources of uncertainties
include the set of assumptions used in projecting the health impact of
reducing PM. These projections are based on a series of models that
take into account emissions changes, the resulting distributions of
changes in ambient air quality, the estimated reductions in health
effects from changes in exposure, and the composition of the population
that will benefit from the reduced exposure. Each component includes
assumptions, each with varying degrees of uncertainty.
In addition, the EPA historically provided point estimates rather
than just ranges of emission-related effects or only quantifying
emissions when monetizing proved to be too uncertain. Therefore, to
address these concerns, the EPA is refraining from providing primary
estimates resulting from changes in PM2.5 and ozone exposure
resulting from changes in direct PM2.5, NOX, and
VOC emissions but will continue to quantify the emissions until the
Agency is confident enough in the modeling to robustly monetize those
impacts.
A more robust description of the potential health and welfare
disbenefits associated with emissions increases due to the proposal is
contained in Chapter 2.3 of the DRIA for this proposed rule.
IV. Request for Comment
The EPA is soliciting comment on key aspects of the proposed rule,
although the Agency is not limiting comment to these identified areas.
To facilitate comment on those portions of the rule, the EPA has
indexed each comment solicitation with a unique identifier below (e.g.,
``C-1,'' ``C-2'') to provide a consistent framework for effective and
efficient provision of comments. Accordingly, the EPA asks that
commenters include the corresponding identifier when providing comments
relevant to that comment solicitation. The EPA asks that commenters
include the identifier either in a heading or within the text of each
comment to make clear which comment solicitation is being addressed.
Specifically, the EPA is soliciting comment on the following aspects:
C-1. The EPA requests comment on all aspects of this proposed rule,
including all elements of this preamble, the proposed regulatory
changes, and the DRIA (including projected impacts), that are not
otherwise enumerated below.
C-2. The Tier 3 NMOG+NOX program includes several
specific emission bins from which manufacturers must choose when
certifying each vehicle family, for example, Bins 20, 30, and 50. All
vehicles within a given Bin must have NMOG+NOX emissions
below the Bin value, so a Bin 50 vehicle family must all be at or below
50 mg/mile. In the Tier 4 program, the EPA created several additional
NMOG+NOX Bins with smaller increments between the Bins. For
example, the EPA added Bins 25, 35, 40, and 45. The EPA requests
comment on if the Agency should add to the Tier 3 program the
additional NMOG+NOX Bins available in the Tier 4 program for
MYs 2027 and 2028. Doing so could provide additional flexibility to
vehicle manufacturers for demonstrating compliance with the
NMOG+NOX fleet average standard.
C-3. The EPA requests comments on the use of the ABT program for
NMOG+NOX emissions in MYs 2027 and 2028 and how the use of
the ABT program may affect the cost analysis presented here and in the
DRIA.
C-4. The EPA requests comments on whether the Tier 3 program should
be extended for three MYs, through MY 2029, instead of two MYs.
C-5. The EPA knows that manufacturers have already started
certifying vehicles to the interim and final Tier 4 standards. The EPA
requests comment on the treatment of MYs 2027 or 2028 vehicles
certified to the final Tier 4 standards once the Tier 4 phase-in
schedule is revised. The EPA is presenting the following initial
framework for this issue:
Certificates of conformity issued for interim or final
Tier 4 vehicles will remain valid throughout their full useful life
(FUL). Thus, a manufacturer may keep selling a Tier 4 vehicle under its
Tier 4 certificate of conformity.
The Tier 4 NMOG+NOX sales-weighted values will
be combined with the Tier 3 NMOG+NOX sales-weighted values
from the same MY.
C-6. The EPA requests comment on any modifications of the Federal
OBD requirements needed to support this action for MYs 2027 and 2028
vehicles.
[[Page 28479]]
C-7. The EPA requests comment on the economic impacts of potential
noncompliance with MYs 2027 and 2028 standards, including costs
associated with revised product plans and sunk development costs, to
adjust the economic analysis.
C-8. The EPA requests comment on the challenges associated with
integrating GPFs on light- and medium-duty vehicles in MYs 2027 or
2028, especially regarding what has changed that renders the extensive
public record insufficient to justify manufacturers installing this
technology.
C-9. The EPA requests comment on the projected MYs 2027 and 2028
BEV sales estimates used for assessing the cost and emissions impacts
of this proposal, as detailed in the Draft RIA.
C-10. The EPA requests comment on whether regulated parties have
any significant reliance interests with respect to MYs 2027 and 2028
Tier 4 criteria pollutant standards.
In this action, the EPA is not requesting comment on any provisions
of the Tier 4 program for MYs 2029 and later.
V. Statutory and Executive Order Reviews
Additional information about these statutes and Executive Orders
can be found at https://www.epa.gov/laws-regulations/laws-and-executive-orders.
A. Executive Order 12866: Regulatory Planning and Review and Executive
Order 13563: Improving Regulation and Regulatory Review
This action is an economically significant regulatory action as
defined under section 3(f)(1) of Executive Order 12866. Accordingly, it
was submitted to the Office of Management and Budget (OMB) for review.
Any changes made in response to OMB recommendations have been
documented in the docket. The EPA prepared an analysis of the potential
costs and benefits associated with this action. This analysis, Revision
of Tier 4 Phase-In Schedule for Light-Duty and Medium-Duty Vehicles:
Draft Regulatory Impact Analysis (April 2026) EPA Technical Report EPA-
420-D-26-001 (``DRIA'') is available in the docket, Docket ID No. EPA-
HQ-OAR- 2025-3297. This analysis is described further in section III.B
of this preamble. The estimated cost savings presented in Table 13
include the effects of several sources of uncertainty associated with
the estimates of costs, such as estimates of BEV market share and
variations in catalyst loading in TWCs, which are discussed in Chapter
1 of the DRIA.
Table 13--Estimated Cost Savings
[Millions, 2024$]
------------------------------------------------------------------------
Cost savings (millions,
Calendar year 2024$)
------------------------------------------------------------------------
2027........................................... $690
2028........................................... 1,170
Present Value (3% discount rate)............... 1,770
Present Value (7% discount rate)............... 1,660
------------------------------------------------------------------------
Note: The EPA notes there are uncertainties associated with these cost
savings projections. See section III.A. of this preamble and Chapter 1
of the DRIA for a discussion of uncertainties in the cost savings
projections.
B. Executive Order 14192: Unleashing Prosperity Through Deregulation
This action is expected to be an Executive Order 14192 deregulatory
action.
C. Paperwork Reduction Act (PRA)
This proposed action does not impose any new information collection
burden under the PRA. This proposed action does not change existing
information collection requirements.
D. Regulatory Flexibility Act (RFA)
I certify that this action will not have a significant economic
impact on a substantial number of small entities under the RFA. In
making this determination, the EPA concludes that the impact of concern
for this rule is any significant adverse economic impact on small
entities and that the Agency is certifying that this rule will not have
a significant economic impact on a substantial number of small entities
because the rule relieves regulatory burden on the small entities
subject to the rule. The regulated entities that are subject to the
regulations we are proposing to delay in this proposed rule are vehicle
manufacturers and importers. The EPA is certifying that this proposed
action would not have a significant economic impact on a substantial
number of small entities because the proposed action would relieve
regulatory burden on all entities, including all small entities,
subject to the current rules. The EPA does not anticipate that there
would be any significant adverse economic impact on directly regulated
small entities as a result of these revisions. The EPA has therefore
concluded that this proposed action would, if finalized, relieve
regulatory burden for all directly regulated small entities.
E. Unfunded Mandates Reform Act (UMRA)
This action does not contain an unfunded mandate of $100 million
(adjusted annually for inflation) or more (in 1995 dollars)] as
described in UMRA, 2 U.S.C. 1531-1538, and does not significantly or
uniquely affect small governments. The action imposes no enforceable
duty on any State, local, or Tribal governments or the private sector.
F. Executive Order 13132: Federalism
This action does not have federalism implications. It will not have
substantial direct effects on the States, on the relationship between
the national government and the States, or on the distribution of power
and responsibilities among the various levels of government.
G. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments
This proposed action does not have Tribal implications as specified
in Executive Order 13175. This proposed action would extend the EPA
Tier 3 criteria pollutant standards by two years and amend the phase-in
schedule for the Tier 4 criteria pollutant standards. If finalized, it
would not have substantial direct effects on Tribal governments, on the
relationship between the Federal government and Indian Tribes, or on
the distribution of power and responsibilities between the Federal
government and Indian Tribes, as specified in Executive Order 13175.
Thus, Executive Order 13175 does not apply to this proposed action.
[[Page 28480]]
H. Executive Order 13045: Protection of Children From Environmental
Health Risks and Safety Risks
Executive Order 13045 directs Federal agencies to include an
evaluation of the health and safety effects of the planned regulation
on children in Federal health and safety standards and explain why the
regulation is preferable to potentially effective and reasonably
feasible alternatives. This action is subject to Executive Order 13045
because it is an economically significant regulatory action under
section 3(f)(1) of Executive Order 12866, and the EPA believes that the
environmental health or safety risk addressed by this action may have a
disproportionate effect on children. Furthermore, EPA's Policy on
Children's Health also applies to this action.\68\
---------------------------------------------------------------------------
\68\ See U.S. Environmental Protection Agency. (2026). 2026
Policy on Children's Health: https://www.epa.gov/system/files/documents/2021-10/2021-policy-on-childrens-health.pdf.
---------------------------------------------------------------------------
Children are not expected to experience greater ambient
concentrations of air pollutants than the general population. Children
are more susceptible than adults to air pollution and children tend to
spend increased time outdoors. Children make up a substantial fraction
of the U.S. population and often have unique factors that contribute to
their increased risk of experiencing a health effect from exposures to
ambient air pollutants because of their continuous growth and
development. Children are more susceptible than adults to many air
pollutants because they have (1) a developing respiratory system, (2)
increased ventilation rates relative to body mass compared with adults,
(3) an increased proportion of oral breathing, particularly in boys,
relative to adults, and (4) behaviors that increase chances for
exposure. Even before birth, the developing fetus may be exposed to air
pollutants through the mother that affect development when the mother
is exposed. A qualitative description of the human health and welfare
effects related to emissions changes associated with this proposal is
provided in Chapter 2 of the DRIA for this proposed rule.
I. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
This action is not subject to Executive Order 13211, because it is
not a significant regulatory action under Executive Order 12866.
J. National Technology Transfer and Advancement Act (NTTAA)
This action involves technical standards. Therefore, the EPA
conducted a search to identify potentially applicable voluntary
consensus standards. However, the EPA identified no such standards.
Therefore, the EPA has decided to use EPA standards. The following
standards appear in the amendatory text of this document: California's
2013 OBD-II and California's 2022 OBD-II. No changes are proposed to
this IBR material. California's 2013 OBD-II is referenced in the
amendatory text of this document and has already been approved for
Sec. 86.1806-17. California's 2022 OBD-II was previously approved for
Sec. 86.1806-27, but Sec. 86.1806-27 is proposed to be redesignated
as Sec. 86.1806-29.
VI. Statutory Authority and List of Subjects
Statutory authority for this proposed rule is found at 42 U.S.C.
7401-7675, especially 42 U.S.C. 7521.
List of Subjects
40 CFR Part 85
Environmental protection, Confidential business information,
Imports, Labeling, Motor vehicle pollution, Reporting and recordkeeping
requirements, Research, Warranties.
40 CFR Part 86
Environmental protection, Administrative practice and procedure,
Confidential business information, Incorporation by reference,
Labeling, Motor vehicle pollution, Reporting and recordkeeping
requirements.
40 CFR Part 1066
Environmental protection, Air pollution control, Reporting and
recordkeeping requirements.
Lee Zeldin,
Administrator.
For the reasons stated in the preamble, the U.S. Environmental
Protection Agency proposes to amend parts 85, 86, and 1066 of title 40,
chapter I, of The Code of Federal Regulations as follows:
PART 85--CONTROL OF AIR POLLUTION FROM MOBILE SOURCES
0
1. The authority citation for part 85 continues to read as follows:
Authority: 42 U.S.C. 7401-7671q.
0
2. Amend Sec. 85.1515 by revising paragraphs (c)(2)(xi) and (c)(6) to
read as follows:
Sec. 85.1515 Emission standards and test procedures applicable to
imported nonconforming motor vehicles and motor vehicle engines.
* * * * *
(c) * * *
(2) * * *
(xi) Nonconforming vehicles subject to the provisions of 40 CFR
part 86, subpart S, originally manufactured in OP years 2032 and later
must meet the Tier 4 exhaust emission standards in 40 CFR 86.1811-29,
the Tier 3 evaporative emission standards in 86.1813-17, and the
refueling emission standards in 40 CFR 86.1813-17(b) and have an OBD
system meeting the requirements of 40 CFR 86.1806-29. In cases where
the standard allows or requires demonstrating compliance using emission
credits, each vehicle imported under this paragraph (c) is subject to
the specified fleet average standard.
* * * * *
(6) An ICI may comply with the cold temperature PM standard in 40
CFR 86.1811-29(c) based on an engineering evaluation.
* * * * *
0
3. Amend Sec. 85.2103 by revising paragraph (d)(1)(v) to read as
follows:
Sec. 85.2103 Emission warranty.
* * * * *
(d) * * *
(1) * * *
(v) Batteries serving as a Rechargeable Energy Storage System for
electric vehicles and plug-in hybrid electric vehicles, along with all
components needed to charge the system, store energy, and transmit
power to move the vehicle. This paragraph (d)(1)(v) is optional before
model year 2027 for LDV, LDT1, and LDT2. This paragraph (d)(1)(v) is
optional for LDT3, LDT4, MDPV, and MDVs until they are first certified
to Tier 4 NMOG+NOx bin standards under 40 CFR 86.1811-27(b), not later
than model year 2031.
* * * * *
PART 86--CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES
AND ENGINES
0
4. The authority citation for part 86 continues to read as follows:
Authority: 42 U.S.C. 7401-7671q.
0
5. Amend Sec. 86.1803-01 by revising the definitions for ``Light-duty
program vehicle'', ``Light-duty truck'', ``Medium-duty passenger
vehicle'', ``Medium-duty vehicle'', and ``Tier 4'' to read as follows:
Sec. 86.1803-01 Definitions.
* * * * *
[[Page 28481]]
Light-duty program vehicle means any medium-duty passenger vehicle
and any vehicle subject to standards under this subpart that is not a
heavy-duty vehicle.
Light-duty truck has one of the following meanings:
(1) Except as specified in paragraph (2) of this definition, light-
duty truck means any motor vehicle that is not a heavy-duty vehicle,
but is:
(i) Designed primarily for purposes of transportation of property
or is a derivation of such a vehicle; or
(ii) Designed primarily for transportation of persons and has a
capacity of more than 12 persons; or
(iii) Available with special features enabling off-street or off-
highway operation and use.
(2) Starting in model year 2029, light-duty truck has the meaning
given for ``Light truck'' in 40 CFR 600.002. Vehicles that qualify as
emergency vehicles for any reason under Sec. 86.1803-01 are light-duty
trucks if they are derived from light-duty trucks.
* * * * *
Medium-duty passenger vehicle (MDPV) has one of the following
meanings:
(1) Except as specified in paragraph (2) of this definition,
Medium-duty passenger vehicle means any heavy-duty vehicle (as defined
in this subpart) with a gross vehicle weight rating (GVWR) of less than
10,000 pounds that is designed primarily for the transportation of
persons. The MDPV definition does not include any vehicle which:
(i) Is an ``incomplete vehicle'' as defined in this subpart; or
(ii) Has a seating capacity of more than 12 persons; or
(iii) Is designed for more than 9 persons in seating rearward of
the driver's seat; or
(iv) Is equipped with an open cargo area (for example, a pick-up
truck box or bed) of 72.0 inches in interior length or more. A covered
box not readily accessible from the passenger compartment will be
considered an open cargo area for purposes of this definition.
(2) Starting with model year 2029, or earlier at the manufacturer's
discretion, Medium-duty passenger vehicle means any heavy-duty vehicle
subject to standards under this subpart that is designed primarily for
the transportation of persons, with seating rearward of the driver,
except that the MDPV definition does not include any vehicle that has
any of the following characteristics:
(i) Is an ``incomplete vehicle'' as defined in this subpart.
(ii) Has a seating capacity of more than 12 persons.
(iii) Is designed for more than 9 persons in seating rearward of
the driver's seat.
(iv) Is equipped with an open cargo area (for example, a pick-up
truck box or bed) with an interior length of 72.0 inches or more for
vehicles above 9,500 pounds GVWR with a work factor above 4,500 pounds.
A covered box not readily accessible from the passenger compartment
will be considered an open cargo area for purposes of this definition.
For purposes of this definition, measure the cargo area's interior
length from front to back at floor level with all gates and doors
closed.
(v) Is equipped with an open cargo area with an interior length of
94.0 inches or more for vehicles at or below 9,500 pounds GVWR and for
all vehicles with a work factor at or below 4,500 pounds.
(vi) Is a van in a configuration with greater cargo-carrying volume
than passenger-carrying volume at the point of first retail sale.
Determine cargo-carrying volume accounting for any installed second-row
seating, even if the manufacturer has not described that as an
available feature.
Medium-duty vehicle means any heavy-duty vehicle subject to
standards under this subpart, excluding medium-duty passenger vehicles.
* * * * *
Tier 4 means relating to the Tier 4 emission standards described in
Sec. 86.1811-29. Note that a Tier 4 vehicle continues to be subject to
Tier 3 evaporative emission standards.
* * * * *
0
6. Amend Sec. 86.1805-17 by revising paragraph (d) to read as follows:
Sec. 86.1805-17 Useful life.
* * * * *
(d) Criteria pollutants. The useful life provisions of this
paragraph (d) apply for all emission standards not covered by paragraph
(b) or (c) of this section. This paragraph (d) applies for the cold
temperature emission standards in Sec. 86.1811-29(c). Except as
specified in paragraph (f) of this section and in Sec. Sec. 86.1811-
17, 86.1813-17, and 86.1816-18, the useful life for LDT2, HLDT, MDPV,
and HDV is 15 years or 150,000 miles. The useful life for LDV and LDT1
is 10 years or 120,000 miles. Manufacturers may optionally certify LDV
and LDT1 to a useful life of 15 years or 150,000 miles, in which case
the longer useful life would apply for all the standards and
requirements covered by this paragraph (d).
* * * * *
0
7. Amend Sec. 86.1806-17 by revising the introductory text and
paragraph (a) introductory text to read as follows:
Sec. 86.1806-17 Onboard diagnostics.
Model year 2017 and later vehicles must have onboard diagnostic
(OBD) systems as described in this section. OBD systems must generally
detect malfunctions in the emission control system, store trouble codes
corresponding to detected malfunctions, and alert operators
appropriately.
(a) Vehicles must comply with the 2013 OBD requirements adopted for
California as described in this paragraph (a). California's 2013 OBD-II
requirements are part of Title 13, Sec. 1968.2 of the California Code
of Regulations, approved on July 31, 2013 (incorporated by reference in
Sec. 86.1). We may approve your request to certify an OBD system
meeting some or all provisions from a later version of California's OBD
requirements if you demonstrate that the provisions from the later
version comply with the intent of this section. The following
clarifications and exceptions apply for vehicles certified under this
subpart:
* * * * *
0
8. Redesignate Sec. 86.1806-27 as Sec. 86.1806-29 and amend the
redesignated section by revising the introductory text and paragraph
(g)(1) to read as follows:
Sec. 86.1806-29 Onboard diagnostics.
Model year 2029 and later vehicles must have onboard diagnostic
(OBD) systems as described in this section. OBD systems must generally
detect malfunctions in the emission control system, store trouble codes
corresponding to detected malfunctions, and alert operators
appropriately. Vehicles may optionally comply with the requirements of
this section instead of the requirements of Sec. 86.1806-17 before
model year 2029.
(a) Vehicles must comply with the 2022 OBD requirements adopted for
California as described in this paragraph (a). California's 2022 OBD-II
requirements are part of Title 13, section 1968.2 of the California
Code of Regulations, operative November 30, 2022 (incorporated by
reference, see Sec. 86.1). We may approve your request to certify an
OBD system meeting a complete later version of California's OBD
requirements if you demonstrate that it complies with the intent of
this section. The following clarifications and exceptions apply for
vehicles certified under this subpart:
(g) * * *
(1) Manufacturers may delay complying with all the requirements of
[[Page 28482]]
this section, and instead meet all the requirements that apply under
Sec. 86.1806-17 for LDT3, LDT4, MDPV, and MDVs any vehicles above
6,000 pounds GVWR that are not yet subject to all the Tier 4 standards
in Sec. 86.1811-29.
* * * * *
0
9. Amend Sec. 86.1811-17 by revising paragraph (h)(1) to read as
follows:
Sec. 86.1811-17 Exhaust emission standards for light-duty vehicles,
light-duty trucks and medium-duty passenger vehicles.
* * * * *
(h) Small-volume manufacturers. Small-volume manufacturers may use
the following Tier 3 phase-in provisions:
(1) Instead of the fleet-average FTP standards for NMOG+NOx
specified in this section, small-volume manufacturers may meet
alternate fleet-average standards of 0.125 g/mile through model year
2021, and 0.051 g/mile for model years 2022 through 2028. The following
additional provisions apply for vehicles certified under this paragraph
(h)(1):
(i) Vehicles are subject to exhaust emission standards over the
useful life as specified in Sec. 86.1805-12 through model year 2021,
and as specified in this section starting in model year 2022.
(ii) Gasoline-fueled vehicles may use the E0 test fuel specified in
Sec. 86.113-04 for vehicles certified to bins higher than Bin 70
through model year 2021.
(iii) Vehicles certified under this paragraph (h)(1) may generate
emission credits and they may use banked or traded emission credits
relative to the alternate fleet-average FTP standard for NMOG+NOx only
in model years 2022 through 2028.
(iv) Vehicles are subject to all the other requirements specified
in this section.
* * * * *
0
10. Redesignate Sec. 86.1811-27 as Sec. 86.1811-29 and amend the
redesignated section by revising paragraphs (a) introductory text,
(b)(2), (b)(4)(ii), (b)(5)(ii), (b)(6), and (f) to read as follows:
Sec. 86.1811-29 Criteria exhaust emission standards.
(a) Applicability and general provisions. The criteria exhaust
emission standards of this section apply for both light-duty program
vehicles and medium-duty vehicles, starting with model year 2029.
* * * * *
(b) Exhaust emission standards for 25 and 35[deg]C testing. Exhaust
emissions may not exceed standards over several driving cycles as
follows:
* * * * *
(2) Fully phased-in standards apply as specified in the following
table:
Table 1--To Paragraph (b)(2)--Fully Phased-In Tier 4 Criteria Exhaust Emission Standards\a\
----------------------------------------------------------------------------------------------------------------
NMOG+NOx (mg/ PM (mg/mile) CO (g/mile) Formaldehyde
mile) \b\ \c\ \d\ (mg/mile) \e\
----------------------------------------------------------------------------------------------------------------
Light-duty program vehicles..................... 15 0.5 1.7 4
Medium-duty vehicles............................ 75 0.5 3.2 6
----------------------------------------------------------------------------------------------------------------
\a\ Paragraphs (b)(6) and (f) of this section describe how these standards phase in for model year 2029 and
later vehicles.
\b\ The NMOG+NOx standards apply on a fleet-average basis using discrete bin standards as described in
paragraphs (b)(4) and (6) of this section.
\c\ PM standards do not apply for the SC03, HFET, and ACC II driving cycles specified in paragraphs
(b)(1)(ii)(C) through (G) of this section.
\d\ Alternative CO standards of 9.6 and 25 g/mile apply for the US06 driving cycle for light-duty program
vehicles and medium-duty vehicles, respectively. CO standards do not apply for the ACC II driving cycles
specified in paragraph (b)(1)(ii)(E) through (G) of this section.
\e\ Formaldehyde standards apply only for the FTP driving cycle.
* * * * *
(4) * * *
(ii) Select one of the identified values from table 2 of this
section for demonstrating that your fleet average emission level for
light-duty program vehicles complies with the fleet average
NMOG+NOX emission standard. These FEL values define emission
bins that also determine corresponding emission standards for
NMOG+NOX emission standards for ACC II driving cycles, as
follows:
Table 2 to Paragraph (b)(4)(ii)--Tier 4 NMOG+NOX Bin Standards for Light-Duty Program Vehicles
[mg/mile]
--------------------------------------------------------------------------------------------------------------------------------------------------------
ACC II--Mid- ACC II--Mid- ACC II--Mid-
temperature temperature temperature ACC II--High-
FEL name FTP, US06, intermediate intermediate intermediate ACC II--Early power PHEV
SC03, HFET soak (3-12 soak (40 soak (10 driveaway \b\ engine starts
hours) minutes) \a\ minutes) \b\ \c\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Bin 70.................................................. 70 70 54 35 82 200
Bin 65.................................................. 65 65 50 33 77 188
Bin 60.................................................. 60 60 46 30 72 175
Bin 55.................................................. 55 55 42 28 67 163
Bin 50.................................................. 50 50 38 25 62 150
Bin 45.................................................. 45 45 35 23 57 138
Bin 40.................................................. 40 40 31 20 52 125
Bin 35.................................................. 35 35 27 18 47 113
Bin 30.................................................. 30 30 23 15 42 100
Bin 25.................................................. 25 25 19 13 37 84
Bin 20.................................................. 20 20 15 10 32 67
Bin 15.................................................. 15 15 12 8 27 51
Bin 10.................................................. 10 10 8 5 22 34
Bin 5................................................... 5 5 4 3 17 17
[[Page 28483]]
Bin 0................................................... 0 .............. .............. .............. .............. ..............
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Calculate the bin standard for a soak time between 10 and 40 minutes based on a linear interpolation between the corresponding bin values for a 10-
minute soak and a 40-minute soak. Similarly, calculate the bin standard for a soak time between 40 minutes and 3 hours based on a linear interpolation
between the corresponding bin values for a 40-minute soak and a 3-hour soak.
\b\ Qualifying vehicles are exempt from standards for early driveaway and high-power PHEV engine starts as described in paragraph (b)(5) of this
section.
\c\ Alternative standards apply for high-power PHEV engine starts for model year 2029 as described in paragraph (b)(6)(v) of this section.
* * * * *
(5) * * *
(ii) Vehicles are exempt from the ACC II bin standards for high-
power PHEV engine starts if their all-electric range on the cold-start
US06 driving cycles is at or above 10 miles for model year 2029, and at
or above 40 miles for model year 2030 and later.
(6) The Tier 4 standards phase in over several years, as follows:
(i) LDV, LDT1, and LDT2. Include all LDV, LDT1, and LDT2 in the
calculation to comply with the Tier 4 fleet average NMOG+NOX
standard for 25 [deg]C testing in paragraph (b)(2) of this section. You
must meet other Tier 4 requirements with 60 and 100 percent of your
projected nationwide production volumes in model years 2029 and 2030,
respectively. A vehicle counts toward meeting the phase-in percentage
if it meets all the requirements described in this paragraph (b) and in
paragraph (c) of this section. Fleet average NMOG+NOX
standards apply as follows for model year 2029 through 2032 light-duty
program vehicles:
Table 3 to Paragraph (b)(6)(i)--Declining Fleet Average NMOG+NOX
Standards for LDV, LDT1, and LDT2
------------------------------------------------------------------------
Fleet average
NMOG+NOX
Model year standard (mg/
mile)
------------------------------------------------------------------------
2029.................................................... 21
2030.................................................... 19
2031.................................................... 17
2032.................................................... 15
------------------------------------------------------------------------
(ii) Default phase-in for LDT3, LDT4, MDPV, and MDV. The default
approach for phasing in the Tier 4 standards for LDT3, LDT4, MDPV, and
MDV is for all those vehicles to meet the fully phased in Tier 4
standards of this section starting in model year 2030 for LDT3, LDT4,
and MDPV and in model year 2031 for MDV. Manufacturers using this
default phase-in for medium-duty vehicles may not use credits generated
from earlier model years for demonstrating compliance with the Tier 4
NMOG+NOX standards under this paragraph (b).
(iii) Alternative early phase-in for LDT3, LDT4, MDPV, and MDV.
Manufacturers may use the following alternative early phase-in
provisions to transition to the Tier 4 exhaust emission standards on an
earlier schedule for LDT3, LDT4, MDPV, and MDV:
(A) If you select the alternative early phase-in for LDT3, LDT4,
and MDPV, you must demonstrate that you meet the phase-in requirements
in paragraph (b)(6)(i) of this section based on all your light-duty
program vehicles.
(B) If you select the alternative early phase-in for medium-duty
vehicles, include all medium-duty vehicles in the calculation to comply
with the Tier 4 fleet average NMOG+NOX standard starting in
model year 2029. You must meet other Tier 4 requirements with 60, 80,
and 100 percent of a manufacturer's projected nationwide production
volumes in model years 2029 through 2031, respectively. A vehicle
counts toward meeting the phase-in percentage if it meets all the
requirements described in this paragraph (b) and in paragraph (c) of
this section. Medium-duty vehicles complying with the alternative early
phase-in are subject to the following fleet average NMOG+NOX
standards for model years 2029 through 2033:
Table 4 to Paragraph (b)(6)(iii)(B)--Declining Fleet Average
NMOG+NOXStandards for Medium-Duty Vehicles
------------------------------------------------------------------------
Fleet average
NMOG+NOX
Model year standard (mg/
mile)
------------------------------------------------------------------------
2029.................................................... 140
2030.................................................... 120
2031.................................................... 100
2032.................................................... 80
2033.................................................... 75
------------------------------------------------------------------------
(C) If you select the alternative early phase-in but are unable to
meet all the requirements that apply in model year 2029 for light-duty
program vehicles and either model year 2029 or 2030 for medium-duty
vehicles, you may switch to the default phase-in. Switching to the
default phase-in does not affect certification or compliance
obligations for model years before you switch to the default phase-in.
(iv) Interim Tier 4 vehicles. Vehicles not meeting all the
requirements of this section during the phase-in are considered
``interim Tier 4 vehicles''. Interim Tier 4 vehicles are subject to all
the requirements of this subpart that apply for Tier 3 vehicles except
for the fleet average FTP standard for NMOG+NOX emissions in
Sec. Sec. 86.1811-17 and 86.1816-18. Note that Interim Tier 4 vehicles
also remain subject to the fleet average SFTP and HD-SFTP standards for
NMOG+NOX emissions in Sec. Sec. 86.1811-17 and 86.1816-18,
respectively. Interim Tier 4 vehicles may certify to the 25 [deg]C
fleet average NMOG+NOX standard under this section using all
available Tier 3 bins under Sec. Sec. 86.1811-17 and 86.1816-18.
Interim Tier 4 vehicles are subject to the whole collection of Tier 3
bin standards, and they are not subject to any of the Tier 4 bin
standards specified in this section. Note that manufacturers complying
with the default phase-in
[[Page 28484]]
specified in paragraph (b)(6)(ii) of this section for Interim Tier 4
LDT3, LDT4, and MDPV will need to meet a Tier 3 fleet average
NMOG+NOX standard in model year 2029, while in that same
year LDV, LDT1, and LDT2 will need to meet a Tier 4 fleet average
NMOG+NOX standard. Note that emission credits from those
Tier 3 and Tier 4 light-duty program vehicles remain in the same
averaging set.
(v) Phase-in for high-power PHEV engine starts. The following bin
standards apply for high-power PHEV engine starts in model year 2029
instead of the analogous standards specified in paragraph (b)(4)(ii) of
this section:
Table 5 to Paragraph (b)(6)(v)--Model Year 2029 Bin Standards for High-
Power PHEV Engine Starts
------------------------------------------------------------------------
ACC II--High-
power PHEV
FEL name engine starts
(mg/mile)
------------------------------------------------------------------------
Bin 70.................................................. 320
Bin 65.................................................. 300
Bin 60.................................................. 280
Bin 55.................................................. 260
Bin 50.................................................. 240
Bin 45.................................................. 220
Bin 40.................................................. 200
Bin 35.................................................. 175
Bin 30.................................................. 150
Bin 25.................................................. 125
Bin 20.................................................. 100
Bin 15.................................................. 75
Bin 10.................................................. 50
Bin 5................................................... 25
------------------------------------------------------------------------
(vi) MDPV. Any vehicle that becomes an MDPV as a result of the
revised definition in Sec. 86.1803-01 starting in model year 2029 may
remain subject to the heavy-duty Tier 3 standards in Sec. 86.1816-18
under the default phase-in specified in paragraph (b)(6)(ii) of this
section for model years 2029 and 2030.
(vii) Recordkeeping. Keep records as needed to show that you meet
the requirements specified in this paragraph (b) for phasing in
standards and for complying with declining fleet average standards.
* * * * *
(f) Small-volume manufacturers. Small-volume manufacturers may use
the following phase-in provisions for light-duty program vehicles:
(1) Instead of the 25[deg]C fleet average NMOG+NOx standards
specified in this section, small-volume manufacturers may meet
alternate fleet average standards of 30 mg/mile for model years 2029
through 2031. The 15 mg/mile standard applies starting in model year
2032.
(2) Instead of the phase-in specified in paragraph (b)(6)(i) of
this section for all requirements other than the 25[deg]C fleet average
NMOG+NOx standards, small-volume manufacturers may comply with all
those other requirements starting in model year 2032.
0
11. Amend Sec. 86.1816-18 by revising paragraphs (a) introductory text
and (b)(14) introductory text to read as follows:
Sec. 86.1816-18 Emission standards for heavy-duty vehicles.
(a) Applicability and general provisions. This section describes
Tier 3 exhaust emission standards for complete heavy-duty vehicles.
These standards are optional for incomplete heavy-duty vehicles and for
heavy-duty vehicles above 14,000 pounds GVWR as described in Sec.
86.1801-03. See Sec. 86.1813-17 for evaporative and refueling emission
standards. This section starts to apply in model year 2018, except that
the provisions may apply to vehicles before model year 2018 as
specified in paragraph (b)(11) of this section. This section applies
for model year 2029 and later vehicles only as specified in Sec.
86.1811-29. Separate requirements apply for MDPV as specified in Sec.
86.1811-17. See subpart A of this part for requirements that apply for
incomplete heavy-duty vehicles and for heavy-duty engines certified
independent of the chassis. The following general provisions apply:
* * * * *
(b) * * *
(14) Starting in model year 2029, you may certify vehicles using
the following transitional Tier 4 bins as part of the compliance
demonstration for meeting the Tier 4 declining fleet average NMOG+NOx
standard in Sec. 86.1811-29(b)(6):
* * * * *
0
12. Amend Sec. 86.1823-08 by revising paragraph (f)(1)(iv)
introductory text to read as follows:
Sec. 86.1823-08 Durability demonstration procedures for exhaust
emissions.
* * * * *
(f) * * *
(1) * * *
(iv) For Tier 4 vehicles, the DF calculated by these procedures may
be used for determining compliance with all the standards identified in
Sec. 86.1811-29. At the manufacturer's option and using procedures
approved by the Administrator, manufacturers may calculate a separate
DF for the following standards and driving schedules:
* * * * *
0
13. Amend Sec. 86.1827-01 by revising paragraph (a)(5) to read as
follows:
Sec. 86.1827-01 Test group determination.
* * * * *
(a) * * *
(5) Subject to the same criteria emission standards, or FEL in the
case of cold temperature NMHC or NMOG+NOx standards, except that a
manufacturer may request to group vehicles into the same test group as
vehicles subject to more stringent standards, so long as all the
vehicles within the test group are certified to the most stringent
standards applicable to any vehicle within that test group. For
example, manufacturers may include medium-duty vehicles at or below
22,000 pounds GCWR in the same test group with medium-duty vehicles
above 22,000 pounds GCWR, but all vehicles included in the test group
are then subject to the off-cycle emission standards and testing
requirements described in Sec. 86.1811-29(e). Light-duty trucks and
light-duty vehicles may be included in the same test group if all
vehicles in the test group are subject to the same criteria exhaust
emission standards.
* * * * *
0
14. Amend Sec. 86.1829-15 by revising paragraphs (b)(2) and (3),
(d)(1) introductory text, and (d)(8) and removing paragraph (d)(9). The
revisions read as follows:
Sec. 86.1829-15 Durability and emission testing requirements;
waivers.
* * * * *
(b) * * *
(2) Test vehicles as follows using the test procedures in 40 CFR
part 1066 to demonstrate compliance with cold temperature exhaust
emission standards:
(i) For Tier 3 and Interim Tier 4 vehicles, test one EDV in each
durability group.
(ii) For Tier 4 final vehicles, test one EDV in each test group.
(3) Test one EDV in each test group to the discrete mid-temperature
intermediate soak standard for a 40-minute soak as identified in Sec.
86.1811-29.
* * * * *
(d) * * *
(1) For vehicles subject to the Tier 3 p.m. standards in Sec.
86.1811-17 (not the Tier 4 p.m. standards in Sec. 86.1811-29), a
manufacturer may provide a statement in the application for
certification that vehicles comply with applicable PM standards instead
of submitting PM test data for a certain number of vehicles. However,
each manufacturer must test
[[Page 28485]]
vehicles from a minimum number of durability groups as follows:
* * * * *
(8) Manufacturers may provide a statement in the application for
certification that medium-duty vehicles above 22,000 pounds GCWR comply
with the off-cycle emission standards in Sec. 86.1811-29(e) for all
normal operation and use when tested as specified. Describe in the
application for certification under Sec. 86.1844-01(d)(8) any relevant
testing, engineering analysis, or other information in sufficient
detail to support the statement. We may direct you to include emission
measurements representing typical engine in-use operation at a range of
ambient conditions. For example, we may specify certain transient and
steady-state engine operation that is typical for your vehicles. Also
describe the procedure you used to determine a reference CO2
emission rate, eCO2FTPFCL, under Sec. 86.1845-04(h)(6).
(9) [Reserved]
* * * * *
0
15. Amend Sec. 86.1838-01 by revising paragraph (b)(1)(i)(A) to read
as follows:
Sec. 86.1838-01 Small-volume manufacturer certification procedures.
* * * * *
(b) * * *
(1) * * *
(i) * * *
(A) At or below 5,000 units for the Tier 3 standards described in
Sec. Sec. 86.1811-17, 86.1813-17, and 86.1816-18 and the Tier 4
standards described in Sec. 86.1811-29. This volume threshold applies
for phasing in the Tier 3 and Tier 4 standards and for determining the
corresponding deterioration factors.
* * * * *
0
16. Amend Sec. 86.1844-01 by revising paragraph (d)(11)(iv) to read as
follows:
Sec. 86.1844-01 Information requirements: Application for
certification and submittal of information upon request.
* * * * *
(d) * * *
(11) * * *
(iv) For Tier 4 vehicles with spark-ignition engines, describe how
AECDs comply with the requirements of Sec. 86.1811-29(d).
* * * * *
0
17. Amend Sec. 86.1845-04 by revising paragraph (h) introductory text
to read as follows:
Sec. 86.1845-04 Manufacturer in-use verification testing
requirements.
* * * * *
(h) Off-cycle testing for high-GCWR medium-duty vehicles. Medium-
duty vehicles that are subject to off-cycle standards under Sec.
86.1811-29(e) are subject to in-use testing requirements described in
40 CFR part 1036, subpart E, and 40 CFR 1036.530, with the following
exceptions and clarifications:
* * * * *
0
18. Amend Sec. 86.1860-17 by revising paragraph (a) to read as
follows:
Sec. 86.1860-17 How to comply with the Tier 3 and Tier 4 fleet
average standards.
(a) You must show that you meet the applicable Tier 3 fleet average
NMOG+NOX standards from Sec. Sec. 86.1811-17 and 86.1816-
18, the Tier 3 fleet average evaporative emission standards from Sec.
86.1813-17, and the Tier 4 fleet average NMOG+NOX standards
from Sec. 86.1811-29 as described in this section. Note that separate
fleet average calculations are required for Tier 3 FTP and SFTP exhaust
emission standards under Sec. 86.1811-17.
* * * * *
0
19. Amend Sec. 86.1861-17 by revising paragraphs (b)(5) and (b)(6)
introductory text to read as follows:
Sec. 86.1861-17 How do the NMOG+NOX and evaporative emission credit
programs work?
* * * * *
(b) * * *
(5) Tier 3 credits for NMOG+NOX may be used to
demonstrate compliance with Tier 4 standards without adjustment, except
as specified in Sec. 86.1811-29(b)(6)(ii).
(6) A manufacturer may generate NMOG+NOX credits from
model year 2029 through 2032 electric vehicles that qualify as MDPV and
use those credits for certifying medium-duty vehicles, as follows:
* * * * *
0
20. Amend Sec. 86.1862-04 by revising paragraph (a)(1) to read as
follows:
Sec. 86.1862-04 Maintenance of records and submittal of information
relevant to compliance with fleet average standards.
(a) * * *
(1) Tier 4 criteria exhaust emission standards, including cold
temperature NMOG+NOX standards, in Sec. 86.1811-29.
* * * * *
PART 1066--VEHICLE-TESTING PROCEDURES
0
21. The authority citation for part 1066 continues to read as follows:
Authority: 42 U.S.C. 7401-7671q.
Sec. 1066.801 Applicability and general provisions.
* * * * *
(c) * * *
(1) * * *
(i) The FTP consists of one Urban Dynamometer Driving Schedule
(UDDS) as specified in paragraph (a) of appendix I to 40 CFR part 86,
followed by a 10-minute soak with the engine off and repeat driving
through the first 505 seconds of the UDDS. Note that the UDDS
represents about 7.5 miles of driving in an urban area. Engine startup
(with all accessories turned off), operation over the initial UDDS, and
engine shutdown make a complete cold-start test. The hot-start test
consists of the first 505 seconds of the UDDS following the 10-minute
soak and a hot-running portion of the UDDS after the first 505 seconds.
The first 505 seconds of the UDDS is considered the transient portion;
the remainder of the UDDS is considered the stabilized (or hot-
stabilized) portion. The hot-stabilized portion for the hot-start test
is generally measured during the cold-start test; however, in certain
cases, the hot-start test may involve a second full UDDS following the
10-minute soak, rather than repeating only the first 505 seconds as
described in Sec. 1066.815. These FTP provisions and sampling options
apply equally for cold temperature testing as described in paragraph
(c)(6) of this section.
* * * * *
0
22. Amend Sec. 1066.815 by revising paragraphs (a) through (c) to read
as follows:
Sec. 1066.815 Exhaust emission test procedures for FTP testing.
(a) General. The FTP exhaust emission test sequence for -7 [deg]C
and 25 [deg]C testing consists of a cold-start test and a hot-start
test as described in Sec. 1066.801. Except as specified, the same
procedures apply for gaseous emission measurements you use to calculate
fuel economy.
(b) PM sampling options. Collect PM using any of the procedures
specified in paragraphs (b)(1) through (5) of this section and use the
corresponding equation in Sec. 1066.820 to calculate FTP composite
emissions, except that you must use the procedures specified in
paragraph (b)(7) of this section for HEV testing at 25 [deg]C. Testing
must meet the requirements related to filter face velocity as described
in Sec. 1066.110(b)(2)(iii)(C), except as specified in paragraphs
(b)(5) and (6) of this section. For procedures involving flow
weighting, set the filter face velocity to a weighting target of 1.0 to
meet the requirements of Sec. 1066.110(b)(2)(iii)(C). Allow filter
face velocity to decrease as a percentage of the weighting factor if
the weighting
[[Page 28486]]
factor is less than 1.0 and do not change the nominal CVS flowrates or
secondary dilution ratios between FTP or UDDS test intervals. Use the
appropriate equations in Sec. 1066.610 to show that you meet the
dilution factor requirements of Sec. 1066.110(b)(2)(iii)(B). If you
collect PM using the procedures specified in paragraph (b)(5) or (6) of
this section, the residence time requirements in 40 CFR 1065.140(e)(3)
apply, except that you may exceed an overall residence time of 5.5 s
for sample flow rates below the highest expected sample flow rate.
(1) You may collect a separate PM sample for transient and
stabilized portions of the cold-start UDDS and the hot-start UDDS with
three bags. Use the stabilized portion of the cold-start test (bag 2)
in place of the stabilized portion of the hot-start test (bag 4).
(2) You may collect a separate PM sample for transient and
stabilized portions of the cold-start UDDS and the hot-start UDDS with
four bags.
(3) You may collect PM on one filter over the cold-start UDDS and
on a separate filter over the hot-start UDDS.
(4) You may collect PM on one filter over the cold-start UDDS (bag
1 and bag 2) and on a separate filter over the 867 seconds of the
stabilized portion of the cold-start UDDS and the first 505 seconds of
the hot-start UDDS (bag 2 and bag 3). Note that this option involves
duplicate measurements during the stabilized portion of the cold-start
UDDS.
(5) You may collect PM on a single filter over the cold-start UDDS
and the first 505 seconds of the hot-start UDDS using one of the
following methods:
(i) Adjust your sampling system flow rate over the filter to weight
the filter face velocity over the three intervals of the FTP based on
weighting targets of 0.43 for bag 1, 1.0 for bag 2, and 0.57 for bag 3.
(ii) Maintain a constant sampling system flow rate over the filter
for all three intervals of the FTP by increasing overall dilution
ratios for bag 1 and bag 3. To do this, reduce the sample flow rate
from the exhaust (or diluted exhaust) such that the value is reduced to
43% and 57%, respectively, of the bag 2 values. For constant-volume
samplers, this requires that you decrease the dilute exhaust sampling
rate from the CVS and compensate for that by increasing the amount of
secondary dilution air.
(6) You may collect PM on a single filter over the cold-start UDDS
and the full hot-start UDDS using one of the following methods:
(i) Adjust your sampling system flow rate over the filter to weight
the filter face velocity based on weighting targets of 0.75 for the
cold-start UDDS and 1.0 for the hot-start UDDS.
(ii) Maintain a constant sampling system flow rate over the filter
for both the cold-start and hot-start UDDS by increasing the overall
dilution ratio for the cold-start UDDS. To do this, reduce the sample
flow rate from the exhaust (or diluted exhaust) such that the value is
reduced to 75% of the hot-start UDDS value. For constant-volume
samplers, this requires that you decrease the dilute exhaust sampling
rate from the CVS and compensate for that by increasing the amount of
secondary dilution air.
(7) For HEV testing at 25 [deg]C, you must operate the vehicle and
collect PM over a full cold-start UDDS and a full hot-start UDDS. You
may use any of the methods described for four-bag sampling in
paragraphs (b)(2) through (6) of this section.
(c) Gaseous sampling options. Collect gaseous samples using one of
the following procedures:
(1) Except as specified in paragraph (c)(2) of this section, you
must collect separate gaseous samples for transient and stabilized
portions of the cold-start UDDS (bag 1 and bag 2) and for the transient
portion of the hot-start UDDS (bag 3). Do not collect a sample for the
stabilized portion of the hot-start test (bag 4), even if testing
includes vehicle operation over a full hot-start UDDS. Exceptions for
certain circumstances apply as follows:
(2) For HEV testing at 25 [deg]C, you must operate the vehicle over
a full cold-start UDDS and a full hot-start UDDS. Collect gaseous
samples separately or together for the transient and stabilized
portions of each UDDS (bag 1 and bag 2 together or separately, and bag
3 and bag 4 together or separately). Collect gaseous samples as
described in paragraph (c)(1) of this section for HEV testing at -7
[deg]C.
* * * * *
0
23. Amend Sec. 1066.830 by revising paragraph (b) to read as follows:
Sec. 1066.820 Composite calculations for FTP exhaust emissions.
* * * * *
(b) Calculate the final composite gaseous test results as a mass-
weighted value, e[emission]-FTPcomp, in grams per mile using
the following equation:
[GRAPHIC] [TIFF OMITTED] TP18MY26.024
Where:
mc = the combined mass emissions determined from the
cold-start UDDS test interval (generally known as bag 1 and bag 2),
in grams.
Dct = the measured driving distance from the transient
portion of the cold-start test (bag 1), in miles.
Dcs = the measured driving distance from the stabilized
portion of the cold-start test (bag 2), in miles.
mh = the combined mass emissions determined from the hot-
start UDDS test interval in grams. This is the hot-stabilized
portion from either the first or second UDDS (bag 2, unless Sec.
1066.815(c) requires you to measure bag 4), in addition to the hot
transient portion (bag 3).
Dht = the measured driving distance from the transient
portion of the hot-start test (bag 3), in miles.
Dhs = the measured driving distance from the stabilized
portion of the hot-start test (bag 4), in miles. Set Dhs
= Dcs for testing where the hot-stabilized portion of the
UDDS is not used for emission sampling.
* * * * *
0
24. Amend Sec. 1066.830 by revising the introductory text to read as
follows:
Sec. 1066.830 Supplemental Federal Test Procedures; overview.
Sections 1066.831 and 1066.835 describe the detailed procedures for
the Supplemental Federal Test Procedure (SFTP). This testing applies
for Tier 3 vehicles subject to the SFTP standards in 40 CFR 86.1811-17
or 86.1816-18. The SFTP test procedure consists of FTP testing and two
additional test elements--a sequence of vehicle operation with more
aggressive driving and a sequence of vehicle operation that accounts
for the impact of the vehicle's air conditioner. Tier 4 vehicles
subject to 40 CFR 86.1811-29 must meet
[[Page 28487]]
standards for each individual driving cycle.
* * * * *
[FR Doc. 2026-09905 Filed 5-15-26; 8:45 am]
BILLING CODE 6560-50-P