No easy answer for the Toyota problem

By Jeremy Anwyl
Tuesday, March 16, 2010

Lately it seems that each day brings another report of a driver's terrifying experience with an out-of-control Toyota. There have been at least four congressional hearings in as many weeks.

Even the most confident consumer has to wonder what is causing all this and, more fundamentally, whether Toyotas are safe to drive.

The second question is easier to answer. Despite the flurry of reports, incidents with speeding vehicles are rare. And vehicles today, including Toyotas, are safer than ever.

While we have heard much recently about "smart pedals," floor mats and sticky throttles, it has not been made clear what is behind the incidents of sudden acceleration. The National Highway Traffic Safety Administration has been investigating sudden vehicle acceleration for a few decades, but it has little new to offer since the 1989 Audi investigation. During that time the agency reported that many incidents of sudden or unintended acceleration by Audi drivers were caused when drivers stepped on the gas instead of the brake.

Ultimately, Audi and other automakers implemented features that required brakes to be depressed when shifting gears out of park, and reports of sudden acceleration when drivers started their cars dropped noticeably.

But as vehicles have become more advanced and, presumably, safer, complaints have still been logged.

As a consumer resource for automotive information, Edmunds.com has a stake in finding answers. We also have a data team that crunches numbers, and we have vehicle testers, both of which we recently assigned to help solve the mystery of unintended acceleration.

We assigned 25 staffers to review, line by line, the published consumer complaint data available on the NHTSA Web site. The database, with more than 760,000 records, is, simply put, a mess. After reading each complaint since model-year 2005, we found that 30 percent of the original complaints were miscategorized; more than 26 percent were duplicates; and hundreds were not complaints but merely comments or suggestions.

When we focused on the major automakers and limited our review to recent-model-year vehicles (2005 to present), the 52,000 complaints through September 2009 -- a fair stopping point, because it was before news reports erupted -- showed that every car company had incidents of sudden acceleration. This is not strictly a Toyota issue. NHTSA head David L. Strickland said as much when he told Congress recently that Toyota's rate of complaints was "unremarkable."

And for driver error to be the likely culprit, a simple statistical review of complaint data should show a relatively uniform distribution across automakers. But our review of NHTSA data showed variations in complaints by manufacturer. While human error may be a factor, it's not the only cause.

Theories about sudden acceleration broadly fall into four categories: First, some sort of electrical interference or computer glitch. Second, a general mechanical failure, such as a sticky throttle. Third, design factors such as floor mats (meaning that the vehicle was functioning correctly, but a design lapse increased the chance of an incident). Fourth, driver error, also known as pedal misapplication.

We tried to re-create the circumstances surrounding some recent incidents. We took the highest-horsepower Toyota Camry to the test track to see whether the brakes could stop a runaway vehicle -- which they can. Next we looked at the Toyota Prius. We found that when the vehicle is accelerating, a simple tap of the transmission shifter into neutral disengages the throttle, and the vehicle coasts to a halt -- even if the brakes are not applied.


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