[Federal Register Volume 61, Number 187 (Wednesday, September 25, 1996)]
[Notices]
[Page 50372]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-24574]


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DEPARTMENT OF TRANSPORTATION

Denial of Motor Vehicle Defect Petition

    This notice sets forth the reasons for the denial of a petition 
submitted to NHTSA under 49 U.S.C. Sec. 30162 for the agency to 
commence a proceeding to determine the existence of a defect related to 
motor vehicle safety.
    On February 28, 1996, Mr. R.A. Whitfield of Crownsville, Maryland, 
submitted a petition asking NHTSA to determine whether the Suzuki 
Samurai 4x4 convertible sport utility vehicle contains a safety-related 
defect. The petition describes the alleged defect in this vehicle as a 
particular vulnerability to untripped or ``friction'' rollovers that do 
not require tripping of the vehicle (e.g. from an impact between the 
wheels and a curb) to initiate the roll, but instead occur in tight 
turns or crash avoidance maneuvers and result from the lateral drag of 
friction generated by the tires and the roadway surface. The petitioner 
attributed this untripped rollover vulnerability to what he 
characterized as the vehicle's very low roll stability and light 
weight, as well as to the high ratio of the occupants' mass to the 
vehicle mass, especially when the Samurai is loaded with passengers. 
Additionally, the petitioner asked NHTSA to determine whether the 
vehicle can safely carry passengers up to its claimed gross vehicle 
weight rating.
    In 1988, the agency investigated the alleged rollover propensity of 
the Suzuki Samurai and two variants of this vehicle, the SJ410 and 
LJ80, in response to two petitions (DP88-011 and DP88-019). In the 
course of this investigation, NHTSA conducted its own vehicle testing 
and analyzed a large body of data, including accident and test data of 
these and other vehicles. However, NHTSA did not decide that the 
Samurai vehicles contained a safety-related defect, largely because the 
information available did not show that the rollover accidents were 
caused by a defect in the vehicle rather than by driver and/or 
environmental factors.
    This petition did not provide any significant new evidence that 
bears on the issue of whether a safety-related defect exists in the 
Samurai. The only ``new'' information presented in the petition was the 
allegation that the Samurai 4x4 convertible sport utility vehicles 
cannot safely carry the number of occupants for which it has seats 
without affecting its propensity to roll over in a fatal crash.
    The petitioner asserted that the cause of the subject vehicle's 
apparent disproportionate involvement in single-vehicle rollover-
initiated fatal crashes is the very low roll stability and the high 
ratio of the occupants' mass to the vehicle mass, especially when the 
Samurai is loaded with passengers. This conclusion relies heavily on a 
statistical regression analysis which shows that the Suzuki Samurai 4x4 
convertible has a higher percentage of identified friction rollovers in 
fatal, single-vehicle crashes as the number of its occupants increases. 
The petitioner further concluded that additional control variables such 
as roadway speed limit, driver age, and pavement condition are not 
statistically significant.
    Contrary to the petitioner's analysis, the Samurai has a track 
width to center of gravity ratio higher than that of most other light 
sports utility vehicles. This ratio has been demonstrated to have a 
fundamental effect on the rollover propensity of vehicles.
    Those vehicles with higher ratios tend to have lower rollover 
propensity. There is also evidence that the subject vehicle has a lower 
sensitivity to mass ratio than many other sport utility vehicles. 
Vehicles with a higher sensitivity to mass ratio demonstrate an 
increased propensity for rollover with the addition of mass that raises 
their center of gravity.
    Based on a statistical analysis, the petitioner stated that more 
than 5,000 persons were occupants in Suzuki Samurai light utility 
vehicles that rolled over in single-vehicle crashes during 1988-1993 
and more than 1,700 of these occupants were injured. He also stated 
that 46 percent of all Suzuki Samurai crashes in 1992-1993 were 
untripped rollover crashes. These are not actual numbers but estimates 
based on a very small sample size, which neglect many unknown 
variables, especially the driver and environmental factors. Moreover, 
one must always exercise great caution in the use of public reported 
accident statistics in evaluating alleged defects, such as that 
addressed in this petition. These statistics are heavily influenced by 
driver and environmental causes that tend to obscure vehicle causes. 
The petitioner's regression analysis does not overcome this difficulty. 
In fact, previous investigations demonstrate that many of the rollovers 
which have occurred appear to have involved adverse driver and 
environmental factors such as high risk driving maneuvers, drinking, 
ambient light, vehicle/road familiarity, etc.
    Although the rollover crash involvement rate of the Samurai is no 
worse than that of most other light utility vehicles, it is 
significantly higher than most passenger vehicles. In a notice of the 
denial of a petition for rulemaking (52 FR 49037, December 29, 1987), 
NHTSA stated that while the agency recognized the existence of a higher 
rollover rate in light utility vehicles, there was no basis for 
proceeding with rulemaking based on stability factors alone because of 
the importance of other vehicle factors, the lack of predictiveness of 
the stability factor for vehicle rollover involvement, and statutory 
limitations that may preclude standards that have the effect of 
eliminating classes of motor vehicles. Similarly, the stability factor 
distinction does not appear to be an appropriate basis on which to 
conduct a defect investigation analysis.
    After reviewing the petition and its supporting materials, as well 
as information furnished by Suzuki and within the agencys possession 
from previous rulemaking proceedings and other actions, NHTSA has 
concluded that further investigation of the Suzuki Samurais rollover 
propensity is not likely to lead to a decision that the vehicle 
contains a safety-related defect and that a further commitment of 
agency resources on this matter is not warranted. The agency has 
accordingly denied the petition.

    Authority: 49 U.S.C. 30162 (d); delegations of authority at CFR 
1.50 and 501.8.

    Issued on: September 19, 1996.
Michael B. Brownlee,
Associate Administrator for Safety Assurance.
[FR Doc. 96-24574 Filed 9-24-96; 8:45 am]
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