Vehicle Rollover Crashes Is The Leading Cause Of Deaths. Seeking to curb demand for vehicles prone to rollover crashes, a leading cause of deaths on U.S. highways, federal auto safety regulators began providing more details Monday about the stability of some popular cars and trucks.
Until now, the National Highway Traffic Safety Administration has provided a five-star rating system that was criticized by safety advocates because it sometimes gave better scores to vehicles that tip during a road test than those that stayed on all four tires.
The new government information indicates how likely on a percentage basis a vehicle is to roll over in a single-vehicle crash.
Among 2004 models the agency tested, the five-star Mazda RX-8 four-door sedan has an 8 percent chance of rolling over the lowest of all vehicles tested.
The two-star Ford Explorer Sport Trac 4×2 sport utility vehicle has a 34.8 percent chance of rolling over in a single vehicle crash, the agency said.
A slew of the most popular Detroit-made SUVs were also near the bottom of the ratings, including the 4×2 versions of the Mercury Mountaineer, Ford Explorer, GMC Yukon and Chevy Tahoe. All of the SUVs have a 28 percent chance of rolling over in a single vehicle accident.
On the whole, SUVs were significantly more rollover prone than cars and minivans.
The agency awards five stars to vehicles that roll over 10 percent of the time or less, and one star to vehicles that roll over between 40 and 50 percent of the time.
“We believe we can accomplish a lot with consumer information,” NHTSA Administrator Jeffrey Runge said at a press conference. “If no one buys vehicles prone to roll over, manufacturers will stop making them.”
The new information also will give car buyers a gauge of how well a vehicle stacks up against models in the same class, such as minivans, SUVs or pickup trucks.
Though rollover crashes only represent about 3 percent of accidents, they account for more than 10,000 death, a third of annual highway fatalities.
Automakers support the agency’s move to provide more consumer information, but caution shoppers not to put too much weight on one measurement.
Vehicle’s Stability Can Be Influenced By An Array Of Factors
A vehicle’s stability can be influenced by an array of factors, such as height, the width between tires, the design of its suspension system, tire grip, the location of the engine mount and even the weight of its sunroof, NHTSA engineers say. About 75 percent of passengers who die in a rollover accident also aren’t belted, government data shows.
Also, while having several passengers can make a low-riding sedan even more stable, high-riding sport utility vehicles become even more unstable with extra people, said R. David Pittle, senior vice president of technical policy at Consumers Union, publisher of Consumer Reports magazine.
“Rather than understand it, the important thing for consumers to know is there is a test devised by the government” to measure it, said Pittle, who thinks the road test is a “very good indicator of vehicle safety.”
“We will never recommend a vehicle that has failed this test,” added Pittle, who considers a vehicle that tips off two tires a failure. “There are too many safer alternatives.”
NHTSA uses three sets of tests and information to compute the scores. It uses real-world accident data, a calculation that essentially measures center of gravity, and a dynamic test maneuver whereby a vehicle is quickly turned one way and then sharply the other way.
That so-called “fishhook” test, unveiled in October, is supported by safety advocates but they believe NHTSA should give more weight to the test results, particularly whether a vehicle “tipped” or not.
For example, the Toyota Tacoma 4×2 extended cab pickup truck got the second highest rating, four stars, even though it tipped during the test.
General Motors Corp. and Ford Motor Co. said NHTSA’s moving rollover test is extremely severe and leads to only 5 percent of all actual rollovers. In real-world driving situations, most vehicles are stable and resist rollover, GM and Ford say.
“It’s very difficult to rate an automobile like you rate a movie, because whenever you summarize information you always lose something,” said Gloria Bergquist, vice president of the Alliance of Automobile Manufacturers, a trade group that represents Detroit and other automakers. “We encourage consumers to become very informed about many different aspects of their vehicle, not to just look at one star rating or another.”
Ford Motor Co. spokeswoman Kristen Kinley said the ratings have some value, but the automaker doesn’t think they are an accurate reflection of real-world crash statistics.
“It’s an estimate of risk, but it’s not a prediction of a likelihood of a crash,” Kinley said.
To enhance safety of SUVs, which are more prone to roll over, some automakers are already installing electronic stability technology, which senses when a vehicle starts to tip and automatically slows it down.
Such systems come standard on several General Motors Corp. vehicles, including the Cadillac Escalade and the GMC Denali, said GM spokesman Chris Preuss.
Ford announced last month that it will equip its best-selling Ford Explorer and three other sport utility vehicles with standard anti-rollover technology, beginning with 2005 models.
A former NHTSA administrator said automakers ought to be forced to demonstrate their vehicles’ safety.