U.S. Department of Transportation
The U.S. Department of Transportations National Highway
Traffic Safety Administration (NHTSA) last week posted model
year 2004 rollover resistance scores that, for the first time,
use the agencys enhanced rating system. It now includes
results from a dynamic track test.
The rollover scores are available at www.nhtsa.dot.gov or
consumers can go to the results directly at: www.safercar.gov/.
While none of the vehicles achieved the agencys highest,
five-star rating, several earned four-star designations, including
the Chevrolet Trailblazer 4x4, Chevrolet Silverado extended
cab (4x4 and 4x2), Ford Focus wagon, Subaru Outback wagon,
Toyota Echo and Volvo XC90 4x4.
A five-star rating means the likelihood of rollover during
a single vehicle crash is less than 10 percent; four-star,
between 10 and 20 percent; three-star, between 20 and 30 percent;
two-star, between 30 and 40 percent; and one-star, greater
than 40 percent.
Other rated vehicles were the Chevrolet Trailblazer 4x2,
Ford Explorer Sport Trac 4x2, Jeep Liberty 4x4 and 4x2, Toyota
4Runner 4x4 and 4x2 and Toyota Tacoma extended cab 4x4. Tests
for several other vehicles are under review and will be released
at a later date. These are the Ford Explorer 4x4 and 4x2,
Ford Explorer Sport Trac 4x4, and Toyota Tacoma extended cab
The dynamic test uses the so-called "fishhook"
maneuver a series of abrupt turns at varying speeds.
A computerized steering system is used in each test vehicle
to maintain objectivity.
NHTSA in the past based its rollover ratings on a vehicles
static stability factor, which is an engineering calculation
based on the track width and the height of the center of gravity.
Beginning with the 2004 model year, the rollover risk predictions
are based on the static stability factor scores and the vehicles
performance in a dynamic track test.
A table showing the test results is on the Internet at www.nhtsa.dot.gov.
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