While applying the brakes to slow down or to come to a stop, if the car hits a bump, pothole or the like, the brakes release momentarily, causing the car"S momentum to continue forward longer/further than you would normally expect or want. This is especially dangerous when coming to a stop at a New York city pedestrian crosswalk or trying to slow down with a car close in front of you. I brought the car into the dealership and had it evaluated by Toyota's field technical specialist who reported the following, ""when [the car] senses impending wheel slip, it will first disable the regenerative brakes. When it does that it feels like the car sort of accelerates because you lost the regenerative braking and you're using the brake assist that you have from your foot. So that is 'normal operation' on the system. It is working as designed." Despite the explanations for why this is happening and whether or not this is ?normal operation", the bottom line is, if the car is not stopping when it should, the safety of passengers and pedestrians is in jeopardy. I called and wrote two certified letters to Toyota's customer experience department and to akio Toyota, and received a phone call from an executive analyst from the president's office. No Toyota representative would do anything in regards to the problem--they maintain that the braking operation is normal. I have seen other complaints on the NHTSA web site and on Prius owners blogs that contradict Toyota's assertion and support the claim that the brakes are indeed a safety issue that must be addressed.

- New York, NY, USA

Re: 2010 Prius. When braking over a pothole, the car surged forward suddenly (sudden acceleration despite braking).

- Newtown, PA, USA

My new 2010 Prius accelerated on it's own as I was braking and slowly approaching the car in front of me that was stopped at a stop light quite some distance away. My car had almost come to a complete stop when suddenly the engine revved on it's own as my foot was still on the brake. I had to press down so hard on the break to keep it from surging forward that the ABS light came on and then the car's rev went down on it's own and all was back to normal and hadn't happened again since. I brought the car to the dealer and they kept it for two days but didn't find anything wrong with it. I have two small children and bought this car for a number of reasons, safety being one of the important ones. I am no longer feeling safe. This was not the floor mats, or a sudden stop mistaking one pedal for another, or any other form of driver error. This was the car! please help to discover the cause and make Toyota fix it before someone gets hurt or killed. Thank you, chris toppin

- Jamaica Plain, MA, USA

On three occasions, while driving on clean, dry road surfaces, my 2010 Prius suddenly and briefly accelerated without any warning after I drove over minor bumps and, one 1 occasion, a manhole cover, while braking. The sensation was that of the engine suddenly surging and accelerating. I was fortunately able to apply harder pressure to the brake pedal, regained control of the vehicle and avoided crashing into the car in front of me. I spoke with a Toyota field technical specialist today who told me that the mechanics of the car are such that if a wheel hits a bump or moves onto a surface that causes it to rotate at a different rate versus the other wheels, the car thinks it is going into a skid, and the ABS system kicks in. Also, the system that generates energy to recharge the battery, which also effectively brakes the car, suddenly ceases to operate. Consequently, you have the sensation of acceleration when in fact, according to the Toyota specialist, the car stopped decelerating. Nonetheless, this sudden deceleration is unexpected, and if I was not focused at those exact moments and failed to immediately apply significant pressure to the brake pedal, I could have easily crashed into an object, or car, or person, in front of me. I do not feel safe in this car, and am worried that my wife or son could have a major problem responding to this sudden lack of control. There is great potential for serious injury or death from this type of incident. My car is about 1 month old, with 1,250 miles on it. I understand from the specialist that Toyota dealerships on long island have had at least one other similar complaint.

- Dix Hills, NY, USA

The contact owns a 2010 Toyota Prius. While driving over large and small speed bumps the vehicle accelerated without warning. As a consequence his risk for serious injury and crash were increased. He is in the process of having the vehicle inspected to determine the cause of the failure. The failure and current mileages were 1,000. Updated 09/14/09 the consumer stated on 6 separate occasions, with 2 different drivers, sudden, brief and unexplained engine acceleration was experienced when a bump was hit in the road while applying the brakes. The driver could hear the engine rev up and there was a surge of power from the engine despite his foot not being on the accelerator, but being on the brake. In each of the 6 incidents the consumer and second driver were able to stop safely, bit were put at risk of an accident and/or injury due to the erroneous acceleration. Updated 09.15.09. Updated 10/13/09. The consumer stated the cruise control was not engaged and it didn't feel like the anti-lock brakes engaged either. Updated 10/13/09 the consumer also experienced braking problems as well. The consumer stated the problem has greatly diminished. Updated 02/05/10.

- Lansdale, PA, USA