Problem is onset of acceleration when brakes applied in 2010 Prius 4, purchased at antwerpen Toyota, clarksville, md in August 2010. Problem has been detected 2 times, without accident, but with significant increase in anxiety. Both incidents were approaching a stop sign, and seemed to be related to change in acceleration due to rapid braking. First incident in September 2009 was considered a 'driver issue' since I had owned the Prius only 1 month. However, second incident in November 2009 was clearly not a driver issue, and was initiated the same way--stopping at a stop sign after driving at highway speeds for some time. Neither incident involved a traffic accident.

- Laurel, MD, USA

On 7 different occasions since purchasing our Toyota Prius 6 months ago, while pushing the brakes, the car has lurched forward as though someone pushed down on the gas.

- Plano, TX, USA

My Toyota Prius 2010 (5000 miles) few times already has an "accelerator that goes wild", but luckily for me, I can hit the brakes. It happened only when I drive back from my garage.

- San Diego, CA, USA

The contact owns a 2010 Toyota Prius. While driving 10 mph with the brake pedal engaged, the vehicle accelerated on its own. The contact was forced to apply pressure to the brake pedal in order to stop the vehicle. The contact has owned the vehicle for 5 months and the failure has occurred twice. The dealer was called and stated that they have not received any recalls for his vehicle; however, to bring it into to the dealership for a diagnostic test. No repairs have been made to the vehicle. The failure mileage was unknown and the current mileage was 3227. Updated 03/12/10. Updated 08/30/10

- Batavia, NY, USA

Brake failure on our 2010 Prius. Updated 02/17/10 the consumer also stated he experienced sudden acceleration. Updated 03/05/10

- Pompano Beach , FL, USA

I have a 2010 Toyota Prius. Sometimes, particularly when I'm driving over bumps, applying the brake actually causes the vehicle to nudge forward instead of slowing down. Once I have cleared the bumps, the brakes then take effect. The problem is that the car may not actually slow down for an extra 10 to 20 feet. There was one incident where this happened near a crosswalk where people were crossing the road. The car stopped in time, but this could have easily turned tragic. Toyota has said nothing about this and don't think there is anything wrong with the car.

- Fair Lawn, NJ, USA

I too have noticed a strange feeling of speeding up instead of slowing down when driving over a large bump on a street in my 2010 Prius.

- New York, NY, USA

I purchased a brand new 2010 Toyota Prius V on September 24, 2009. It performed beautifully, and was a real pleasure to drive. However, a month or so later, with the car in reverse, I started backing out of a parking place and immediately noticed an unusually intense "revving" of the engine. Startled, I immediately pressed on the foot brake, releasing it in little steps until the car was "inched" out of the parking place. I then shifted the lever into "drive" and proceeded on my way quite normally without any further problem whatsoever. In the ensuing months, this strange phenomenon has only repeated itself two more times out of hundreds of backouts from parking slots. There has been no other circumstance in which this severe " revving" has re-occurred. In the aforementioned three cases, I had no recollection whatsoever of pressing the foot throttle, and therefore have presumed that the problem is in the electronics or software, rather than in the floor throttle mechanics. In every other respect so far, my 2010 Toyota Prius V has performed perfectly.

- Palo Alto, CA, USA

At 8:00 am this morning, I was driving through a street at a speed of 20 miles to 30 miles per hour. Suddenly, the car jumped a little probably hit a small potholes or bumps. I felt like the car surged forward or may be the brake didn't respond immediately. Fortunately, no other car right in front of me and the car speed is not very fast. I was able to brake it and slow down. I have called the dealer and the service representative doesn't think it is a problem. Later, I also sent a fax to Toyota us headquarter asking for help.

- Murrysville, PA, USA

My 2010 Prius accelerates when it hits a pot hole while slowing down. This happens more when there is snow or ice on the road. In icy conditions I am slowing down and not pressing on the brake, but if it hits a pot hole -- a momentary loss of control is experience. It seems like the electric brake switches off and hydraulic brakes kicks in because it brakes harder once back.

- Bensenville, IL, USA

While driving with cruise control engaged and a situation occurs that requires braking; normal brake pedal pressure does nothing. I have to hit the brakes extra hard which significantly slows reaction time. This problem occurs randomly. When I took the car to the dealer I could not get the problem to repeat.

- Auburn, WA, USA

The contact owns a 2010 Toyota Prius. While driving 10 mph over railroad tracks engaging the brake pedal the vehicle failed to stop and accelerated. The failure occurred intermittently; therefore, when she took the vehicle to the dealer for routine maintenance, she did not mention the failure. She will take the vehicle back to the dealer to be diagnosed. The failure mileage was 4 and the current mileage was 5,600. Updated 08/12/10

- North Port, NY, USA

Toyota 2010 Prius - problem with car accelerating when I brake on bumpy surface. Has occurred repeatedly as on my drive to work I drive over a potholed section of road and need to brake to slow down for a right hand turn -if I go very slowly and do not brake on the bumpy part it does not occur - when I drive at a normal speed and brake for the turn it does occur - I feel a major acceleration that lasts for only a second or two.

- Kildeer, IL, USA

I own a 2010 Toyota Prius that I purchased in the fall of 2009. On several occasions I have depressed my brake pedal to either slow down or stop but, instead, the vehicle briefly accelerates and gives a feeling of "skipping" over the braking action. The vehicle then quickly corrects before stopping or slowing down. This has happened on more than one occasion on very specific types of terrain that I can describe as bumpy or uneven. I placed a call today with my Toyota dealership in which I explained the above narrative to them. They responded with ignorance to the situation and stated that they will wait to hear from Toyota on the matter.

- Easton, PA, USA

On 8-21-09, I took delivery on a 2010 Toyota Prius hybrid. Since taking delivery, I have experienced intermittent, momentary, unintended acceleration and intermittent, momentary loss of braking. On 1-10-10, I took it in for the 5000 mile maintenance check, but did not tell the dealer my problems, because I thought the car was still in a "breaking in" period and would resolve itself. But when I heard today 2-4-10, that the NHTSA was opening an investigation of the 2010 Prius, I decided to add my complaint to the others. Updated 03/04/10

- Northport, NY, USA

When driving over uneven terrain (ie.; railroad tracks, bumps in the road) my 2010 Prius seems to accelerate. I read about the brakes failing... but it really feels like it is accelerating too. It is very scary when this happens as it feels that you will be thrushed into whatever might be in front of you.

- Columbus, GA, USA

My 2010 Prius (purchased 6/30/09) lurches forward when I hit a pothole or a sharp bump in the road while I have the brakes on. It has happened about 3 times since I've had the car.

- Los Angeles, CA, USA

Sudden unintended acceleration, momentarily loses braking when it goes over uneven roads, potholes..etc. Occurs several times a day.

- Scottsdale, AZ, USA

I have a 2010 Prius. On at least three occasions, in the last six months, the following has occurred. When I am traveling and I apply brake pressure the vehicle begins to accelerate. No matter how hard I press on the brake pedal it does not slow down or stop the vehicle. It actually begins to speeds up while my foot is pressing down on the brake pedal. The acceleration has only lasted approximately 5-6 seconds. However, it is very frightening when you are traveling at a high rate of speed and trying to slow down especially off a freeway off ramp. The last thing you want to do at that time is accelerate even if it is momentarily. This has occurred in various places. It has happened while I am getting off of the freeway and on city streets. There was nothing I did in particular that corrected the failure. The Prius just stopped accelerating on it's own.

- Oxnard, CA, USA

I purchased a new 2010 Toyota Prius in September 2009 from darcars Toyota in frederick md. I have experienced (2) instances of unintended acceleration during the time since I purchased the vehicle. I have informed darcars Toyota and Toyota corporation. Darcars ran a "health test" on February 4, 2009 on my vehicle and the test indicated everything on the vehicle was operating normally. Darcars then contacted their Toyota California (tac) and related my problem to them. The response from Toyota was that my episodes of unintended acceleration was just the ABS system engaging normally. This is after the press release from Toyota corporation on the morning of 02/04/10 acknowledging a problem existing with the 2010 Prius but claiming to have already fixed the problem on all new 2010 Prius automobiles sold since January 2010. My two questions are 1) if Toyota discovered a problem with the 2010 Prius that they supposedly repaired on all 2010 Prius vehicles sold since January, why has Toyota not contacted me about what is an obvious safety issue? I have owned and been driving my 2010 Prius since September '09. 2) what is the specific repair that was supposedly performed on all 2010 Prius automobiles since January 1, 2010" why did my Toyota service manager have no knowledge of such a repair? was there a safety bulletin issued by Toyota" why has Toyota not already agreed to repair my 2010 Prius (sold in September '09) with the same repair allegedly already performed on 2010 Prius automobiles sold after January 1, 2010?

- New Market, MD, USA