Unintended Acceleration in My 2006 Prius
It’s Not the Floor Mats or a Sticky pedal
A 2006 Toyota Prius similar to mine that has unintended acceleration problems
(Updated 5/24/2009) I love my Prius. I have owned it nearly three years and over 30,000 miles. It was a sunny Friday afternoon. I was on my way home from work. It’s a seven mile drive I do twice every day. I was stopped at a light. When the light turned green, I gently eased the brake pedal up. Immediately the Internal Combustion Engine rev’d and the car started surging forward. I jammed my foot back down on the brake. The engine stopped screaming. Again, I gently reduced pressure on the pedal with the same frightening result. Next, I checked the floor to make sure that my heavy rubber floor mat wasn’t touching the gas pedal. The mat was safely under all the pedals. I tried shifting to neutral. No dice. Now , starting to get desperate, I turned the cruise control on and off. That stopped the crisis,
This wasn’t the first time I experienced this problem. On several occasions while stopped at a flow control traffic light on the interstate ramp, when I removed my foot from the gas, the car surged forward. Since I was in the clear and needed to accelerate, I didn’t give it much thought. Once I got my foot on the gas and pressed down and eased off, the problem disappeared. I admit that the behavior was so strange I convinced myself I was imagining things. Now, after the traffic light incident, I realize I wasn’t dreaming.
The rest of the drive home was uneventful. I remember reading that a year or two ago a Prius had driven through the front window of a store. The driver claimed that the Prius just accelerated on its own. I figured the driver just hit the gas instead of the brake. I did a web search on Prius unintended acceleration and found some news articles about similar incidents. Toyota denied there was a problem with the hybrid and intiated a recall of the floor mats, alledging the problem was a front floor mat that slipped and covered the gas pedal. When I called my local dealer, the service manager expressed concern and admitted that this was the first case reported to his dealership. Some of the accounts on the web say the problem is due to a defective cruise control.
How can this happen to any car?
The Prius is the first car that has true drive-by-wire; the gas pedal is not mechanically connected to any part of the car. It is just a potenteometer, like the volume control on a radio. A computer reads the pressure on the pedal and then tells the electric motor, gas engine, or both to move the car. If there is a problem, the computer can accelerate the car without the gas pedal being depressed. In the past, other cars (remember the Audi?) have had runaway acceleration. These problems were mostly due to mechanical linkages being stuck which resulted in the unwanted acceleration. In a Prius, the human driver doesn’t have to participate at all. The onboard computer, like HAL in 2001, can take over on its own.
Does this mean that cars that are computer-controlled are inherently dangerous? Absolutely not. Every commercial airliner is fly-by-wire. Computers, not muscle operates the controls that fly the plane. The Prius is a joy to drive. It has so many innovations contribute to one of the best driving experiences I have ever enjoyed. I consistently get between 40 and 55 miles per gallon (my consumption drops a bit under 40 mpg when it is cold out and the gas engine has to run to warm the car). I love to drive it and have no plans to get rid of the car.
Your driving technique can be life or death
The reason my runaway acceleration incident didn’t result in a life-threatening accident is due to how I learned to drive. Many people are in the habit of just takng their foot off the gas pedal and moving it to the accelerator. I don’t do that. I gently reduce pressure on the brake allowing the car to start rolling. Then I remove my foot from the brake and move it to the gas. Had I just taken my foot off the brake, as many do, my car would have careened down the road, slamming into another car or a pedestrian. I’m lucky that my driver training so many years ago got me into the habit of slowly releasing the brake.
Friday’s incident disproves Toyota’s theory that floor mats cause the problem. When I go to the dealer tomorrow, I am hoping that this problem can be corrected. It would be unsafe to drive a car that could run away like that. Therein lies my problem. The Prius is not Corvair. It’s a superbly built machine that exceeds every expectation I had for a hybrid. Like a 747 or an Airbus, the Prius is a complex, computer-controlled machine. Hundreds of thousands of them are on the road. My Prius has served me well for three years. But there is a problem.
The problem isn’t that Toyota makes unsafe cars. It’s that Toyota isn’t believing its customers. I am a customer who is an engineer, checked all the right things, and verified that this problem is real and dangerous. Stay tuned for how my adventure comes out.
Update (May 4, 2009)
I took the car to the dealer. It was unable to find any problem. This is the same as other people’s experiences with this issue. Now I have to decide what to do next. Probably I will continue to drive the car and hope for the best.
Update (May 22, 2009)
I called the Toyota Experience line. This is the corporate customer service number. I told them about my problem. They told me that unless the dealer can reproduce it, there is nothing they could do. I asked if they had similar reports from others. The rep acknowledged he had, but said that Toyota determined it was “driver error.”
I also contacted the state attorney general’s office. It fowarded the complaint to the “auto dealer” complaint office. Clearly they don’t understand the issue. This isn’t unlike the problem with the Chevrolet Corvair. Until Ralph Nader wrote his landmark book, Unsafe at Any Speed, that exposed General Motors coverup of the Corvair’s gas tank, people died. General Motors had determined that it would cost less to pay death benefits than fix all the defective Corvairs. I have always believed that Toyota was the most honorable of car companies. That belief is badly shaken by the way they are turning a blind eye on this life-threatening problem with the Prius.