Despite ominous news reports of cars careening out of control, there's no substitute for data. And now it looks like many reported cases of so-called "sudden acceleration" in Toyotas are actually due to driver error.

That's the preliminary conclusion coming from investigators at the National Highway Traffic Safety Administration (NHTSA) who analyzed dozens of event-data recorders, or "black boxes," from Toyota models that had crashed.

Black box: Accleration, not braking

The recorders showed that despite drivers' claims that they were pressing the brakes as hard as they could, in fact the accelerators were floored and the brakes were never applied.

That is exactly what happened in the March crash of a 2005 Toyota Prius in the New York City suburb of Harrison, N.Y. There, a 56-year-old housekeeper swore she was braking as hard as she could when the car raced across a busy road, slamming into a stone wall.

In that case, the NHTSA statement all but used the words driver error, saying that the car's onboard computer systems "indicated there was no application of the brakes, and the throttle was fully open."

We've seen this before

The latest conclusions, reported by the Wall Street Journal but not officially confirmed by the agency, involved data recorders selected at random by the agency, not Toyota [NYSE:TM].

The NHTSA has not yet issued a formal statement, saying it will wait to complete a longer study before commenting. But the conclusions are not unexpected among auto-safety experts. Few believe that "sudden acceleration" in the Prius or any other car is possible.

Back in 1989, the agency concluded that drivers were also at fault in so-called "sudden acceleration" cases involving Audi 5000 sedans. That was three years after a notorious documentary.

Misfiring neurons

But how can a driver believe she is braking when in fact she has the accelerator floored? The University of California-Los Angeles professor Richard Schmidt, who teaches psychology, writes, "The trouble, unbelievable as it may seem, is that [it] is very often caused by drivers who press the gas pedal when they intend to press the brake."

The culprit is "noisy neuromuscular processes," in which a limb does something slightly different from what the brain has asked it to do. In this case, the driver's foot may extend at a different angle than the body expects.

Compounding the problem



Panic then exacerbates the situation, with drivers pressing even harder on their "brake" pedals. Which of course keeps the accelerator floored and often leads to a crash.

That said, a handful of cases may have been due to oversize or improperly fitted floor mats in Toyota and Lexus vehicles. The company is now working through millions of vehicles to shorten and modify their accelerator pedals to alleviate the potential for such a problem.

That was the conclusion of the investigation into a notorious crash last August, in which a California Highway Patrol officer and three other passengers were killed when their Lexus accelerated out of control, crashed, flipped over, and burned.

That case is the only one out of more than 3,000 complaints in which the NHTSA has concluded the vehicle was at fault.

[WSJ.com via Fox]