'Brake override:' The fix Toyota should have had

NEW YORK (CNNMoney) -- There's one safety feature that Toyota could have had in its cars for years that would have stopped many, perhaps even most, cases of unintended acceleration -- it's called 'brake override.'

Toyota has been saying for several weeks that it will add the feature to all of its new cars, and singled out the technology again at a press conference in Japan Wednesday.

Brake override -- or "smart throttle" -- is a software algorithm that acts as a tie-breaker between the gas pedal and the brake pedal. Once you step on the brakes, even if the gas pedal is pressed down at the same time, the car assumes you no longer want to accelerate.

The car acts as if you've stepped off gas, dropping the engine speed to idle. A driver could easily stop a car even if the gas pedal were pinned down down to the floor.

"There's an implausibility going on there, so we defer to the brakes," said Rob Moran, a spokesman for Mercedes-Benz, one carmaker that already uses this technology on all of its cars.

Volkswagen also uses this technology on all of its cars, including Audi models, and Chrysler Group uses it on all of its Chrysler, Dodge and Jeep vehicles.

Toyota has said it hadn't previously used the technology because some drivers occasionally choose to use both the brake and gas pedals at the same time for certain maneuvers, such as starting the car on a steep incline.

Some automakers, like General Motors, feel it's not needed. GM has technology similar to brake override, but only on cars like the Corvette ZR1 and Cadillac CTS-V, vehicles with engines so powerful they threaten to overwhelm even strong braking.

A GM spokesman said the brakes on most of its cars are strong enough to stop cars even at full throttle. GM specifically tested this with a Pontiac Vibe, a car engineered by Toyota.

"We ran the Vibe wide open at 60 miles an hour and the brakes were able to bring the vehicle to a safe stop within 169 meters, consistent with our internal requirement for brake performance." said Martin Hogan, GM director of brake systems, in a company statement.

While that may be true under ideal conditions, it doesn't reflect a real-life scenario with a panicked, non-professional driver, according to Jake Fisher, a vehicle engineer for Consumer Reports magazine.

Pumping the brakes, or even just releasing the brake pedal once and pushing it back down, while the car is at full throttle can lead to the loss of power brake pressure. Without that, there's little hope of stopping the car if it's still in gear at full throttle, said Fisher.

If your gas pedal is ever stuck down or the car acts as if it is, step one is to move the gear selector to neutral. Even without "smart brake" technology, you should be able to stop the car.

The brake override system requires a computerized electronic throttle control system, something most newer cars have today.

Car buyers may be nervous about computers running their cars' basic functions, said Fisher. But with an old-fashioned mechanical throttle, there's just a cable communicating between the gas pedal and the engine. If that cable fails or gets stuck, there is no back-up. With software, you can have multiple systems running, checking their inputs and actions against one another.

"Smart-throttle" is just another back-up system, said Fisher, and it's one every car should have. "It may not be the cure-all," he said "but it is absolutely the right thing to do."