Last month, Toyota recalled nearly 4 million vehicles because a faulty floormat design could cause the cars to accelerate out of control if the floormat should slip out of position, holding the gas pedal down. The recall lead many media outlets to post news stories theorizing on how to stop a car that is accelerating out of control. Now, Consumer Reports has tested these theories, using a closed race track and a few cars. Their results are not particularly surprising, but they are important for drivers to understand.
Stopping certain cars turns out to be a fairly simple matter. CR explains, "Our first two subjects were the Mercedes-Benz E350 and Volkswagen Jetta Wagon, German cars with so-called ‘smart-throttle' technology. Both will electronically ignore the throttle input if the brake pedal is depressed." Test drivers drove each car at a steady 60 miles per hour, then stood on the brakes while the gas pedal remained down. "With both vehicles, we were able to safely slow to a stop despite the engine having been at wide-open throttle," they report. "After stopping, the engines idled even with the throttle pedal still floored."
Smart throttle technology is currently found on most Audi, BMW, Volkswagen, and certain Chrysler, Mercedes-Benz and Infinity products.
With other vehicles, however, stopping the car while the accelerator is depressed is a much more difficult proposition. Testers used a Toyota Venza and a Chevrolet HHR, for instance, and were unable to bring the cars to a stop from highway speed using just the brake pedal. CNET explains, "Both cars downshifted quickly when put through this test, and the drivers had to struggle to keep pressure on the brakes, fighting engine torque. But they were able to bring the cars to a stop. Repeating the test on these cars by running up to the full 60 mph, the drivers were able to slow to about 10 mph," but were unable to stop the cars.
Finally, Autoblog reports, the testers followed Toyota's suggested procedure - they slid the car's transmission into neutral, then attempted to brake. Autoblog reports, "It was an action that was equally effective on all four vehicles. The CR team also explored shutting off the engine (turn the key or hold the Start/Stop button down for more than a few seconds). This method also worked well, but doing so killed the power steering pump and brake booster, making maneuvering much more difficult."
So, Toyota's advice to owners still wins - if you find yourself in a car that is accelerating out of control, shift it into neutral and stand on the brakes, but don't shut the car off.