I purchased a 2010 Toyota Prius in August, 2009. During the fall, 2009, I experienced two incidents, which in retrospect, I think involved sudden acceleration. On both occasions, I was driving home from work and went over a spot on the road which, because it was dark, I couldn't see for sure, but which felt like a pot hole. (I also think it may have been raining on both of these occasions, although I can't recall for sure). Immediately after hitting what I think was a pot hole, I felt the car suddenly and dramatically accelerate. Both times I applied the brakes and the car stopped accelerating. At the time, it did not occur to me what was going on. But, now thinking about it, I think it likely that the sudden jolt to the car, perhaps combined with moisture, caused some type of electrical malfunction, which thankfully, was short-lived (or at least stopped by braking). Shortly after these incidents, I mentioned them to my wife. She reported that she had experienced very much the same thing on a separate (I.e., a third occasion) driving our Prius.

- Concord, MA, USA

Sudden acceleration when passing over rough spots(has happened with manhole cover). Braking stops the acceleration.

- Scarsdale, NY, USA

Prius purchased Nov 2009: At least incidents of car lurching forward significantly and momentary sense of loss of control when braking on uneven surface. Occured in Dec 09, Jan 10, and Feb 10. Had a pedestrian been crossing illegally, the person could've been hit bec I could not prevent or control that lurching. This is a dangerous situation. I feel I cannot drive my car safely. I need my car for work. I phoned my Toyota dealer who said to bring it in for evaluation, but they sound tentative. I want a solution and don't want to be making numerous trips from my rural town to the city dealer for guesses.

- Manitowoc, WI, USA

Bought a 2010 Prius in October 2009. It currently has 3500 miles on it. At least three times the car felt as if it slipped on ice when applying the brakes (weather conditions were perfect - no ice, snow or rain). Their is difficulty in clearing fog from the windows and one time I had trouble setting the cruise control.

- Delaware, OH, USA

While driving my wife's 2010 Toyota Prius from Colorado springs to alamosa we experienced the following anomaly. We were on the freeway (I-25) driving South on level terrain with the cruise control set at ~70mph. I noticed a significant increase in the engine RPM and could see the engine display for the engine in the pwr mode. I disengaged the cruise control and waited a short period of time and reengaged the cruise control. A short time later (~15 minutes) the RPM increase occurred again and I once again disengaged the cruise control. I did not use the cruise control again on the trip. My wife has used the cruise control rarely since her use does not include freeway driving.

- Elbert, CO, USA

I own a 2010 Prius purchased around Sept. 2009. A few weeks after we got the vehicle, my wife and I independently both experienced a sudden acceleration when the car went over a bump. This has occurred about a total of 4 times. My foot was not on the accelerator at the time this occurred. Stepping on the brake did slow the vehicle down. The last time I experienced this was 2-3 weeks ago. I did ask the dealer shortly after the initial incident if he had heard of this problem and he said no. I have not since brought the car back to the dealer. We have noticed this only when the car goes over a bump.

- Great Neck, NY, USA

The vehicle is a very new Prius version 3. there is no problem with the floor pads. There does not seem to be a problem at higher speeds. The problem is short, unexpected bursts of acceleration at lower speeds, especially as the car is slowing down, with or without braking. I believe it occurs especially when the engine shifts from hybrid to all electric. For example, on a curving exit ramp off a road, as the car slows, and as braking and acceleration are released, and the car shifts into propelling itself on electric, there is a burst of acceleration at some time in this maneuver. This has happened several times since purchasing the car a few weeks ago. I spoke to the service manager at he dealership last week. He stated he knew nothing about this, and had heard northing from Toyota. He offered to look at the car if I brought it in. Subsequently the Prius problem became news.

- West Nyack, NY, USA

I have experienced the same issues as reported for my 2010 Toyota Prius: The vehicle surged forward or temporarily lost braking(in a split second) after driving over a pothole or other uneven surface.

- Parsippany, NJ, USA

Sudden, unintended acceleration--2010 Prius on freeway, accelerated with gas pedal to 75. Put on cruise control. Several seconds later, car surged forward, hard and sudden acceleration. First time happened--three days ago, not driven since. Have done nothing yet.

- Santa Fe, NM, USA

My husband and I bought a 2010 Toyota Prius in November 2009. We both have noticed a sort of jerky feeling while braking over a small bump or pothole but we didn't think much of it until last night when I was driving home with my children. I was driving down a residential area at about 30 miles/hr. And was slowing down to stop at a red light. While I was braking I hit a medium sized pot hole. My car just leapt forward about 10 feet. I had my foot on the brake firmly the entire time but the car would not stop. Finally my car came to a stop. I was very shaken by this incident. If there was a car in front of me I would have totally rearended them. I came home and immediately called the Toyota dealership. I left a message with the service department. My call was returned by the manager this morning. She said that she had not heard anything from Toyota about any brake issues and then she asked me whether I was speeding! she did not seem to believe me and basically said that there was nothing that they could do.

- Andover, MA, USA

The cruise control on my 2010 Toyota Prius does not always cancel while braking. This has resulted in unintended acceleration after braking while the cruise control has been set. A driver expects that the cruise control will automatically cancel while applying the brakes but this does not happen under light braking. This is even more pronounced while driving up a steep hill. On January 11th, 2010, I was in a situation where I actually applied the brakes to reduce my speed while traveling up a steep hill and felt the car "fighting" against me to maintain a steady speed. After I had slowed my Prius to match the speed of the car in front of me, the cruise control unexpectedly caused the car to accelerate again, placing me at a less than safe distance to the car in front of me as we crested the hill.

- Little Rock, AR, USA

I experience a few times week since last summer when I got my 2010 Prius the "1 second" brake failure that has been reported for 2010 Prius vehicles. As an owner of such vehicle, the pothole on my usual freeway on ramp and the speed bump in my work's parking garage both cause a quick acceleration feeling for about 1/2 second if I'm applying the brakes at the moment of passing over the pothole or speed bump. That 'feeling' may be not an acceleration but a momentary brake failure. The failure is only about 1/2 second and I'm used to it now, though obviously it is an unsafe situation. If I come across such events while, say, braking hard when I see a pedestrian in the parking lot, I could fail to avoid hitting the person.

- Long Beach, CA, USA

I bought at 2010 Prius on 12/26/09 from the very beginning intermittently when I go to stop the car won't stop (my chest tighten) its as if the back of the car is being pushed forward even though you have your foot on the brake. You a get a hesitation and then the car stops. My husband said it was the traction control I was not use to it.but the traction control light does not come on. Its is getting harder and harder to stop. Now even the passengers hear and feel the problem. Yet when I call Toyota to bring the car in they say there is no recall.

- Brooklyn, NY, USA

The contact owns a 2010 Toyota Prius. While driving 2 mph in reverse and removing his foot from the brake, the vehicle accelerated on its own. The failure has occurred approximately 3 to 4 times. The dealer was contacted and had not responded when the complaint was filed. The contact is concerned about the safety risk involved and doesn't feel safe driving the vehicle. No repairs were made to the vehicle. The failure mileage was 2000. The current mileage was 5400.

- Meredith, NH, USA

I've also experienced braking issues with the Prius. This usually happens going over potholes, rough road, or railroad tracks when braking at certain speeds while applying the brakes at moderate force. It momentarily feels like the car is accelerating - it's quite disconcerting. I've also noticed variability in braking distance even on smooth dry pavement where I've had to step harder on the brakes because the car wasn't stopping as expected.

- Bethpage, NY, USA

When the road surface is slippery and/or uneven (I.e, pothole is beginning to form), my 2010 Toyota Prius has "surged" or accelerated suddenly at low speeds under 30 mph, for no apparent reason other than coming into contact with the bumpy/slick road surface. This sudden acceleration responds to braking and has occurred approximately 5-8 times, with more frequency since the rainy weather began. This is frightening for a few brief seconds, especially in heavy traffic. As a consequence, I try to avoid uneven road surfaces but in heavy rain conditions when the road is covered with water, pot holes and brakes in the blacktop are not as easily visible and once I swerved to miss it by moving into the next lane a little bit and a big truck was merging into the same lane at the same time and blew his horn so hard it scared me even more so that I swerved back into my lane, nearly causing an accident. I plan to contact my dealer today about this acceleration defect.

- San Antonio, TX, USA

The contact owns a 2010 Toyota Prius hybrid. While driving approximately 20- 25 mph on a slightly snow covered road surface there was pressure applied to the brake pedal, followed by an unintended acceleration. The driver continuously applied pressure to the brake pedal; however, the vehicle failed to slow down while proceeding through an intersection. An opposing vehicle crashed into the front passenger side and there were no injuries. The police was called to the scene. The vehicle was completely destroyed and towed to a collision center. The VIN was unavailable. The cause of the failure has not been determined at this time. The failure mileage was 7,700. Updated 03/12/10. The consumer stated when he approached a stop sign with adequate distance to stop, pressure was applied to the brake pedal. When the vehicle would not stop, he had to press harder to get the vehicle to stop. Updated 07/13/10.

- Monroe Township, NJ, USA

I have noticed issue with braking. I remember it had rained the previous night and the morning it was freezing. I was driving on rt. 76 to drop my son off to his work. On small stretch of rt. 76 has the 'cement patch' - those you typically see on a over pass. Fearing icing, I hit the brake only to feel it not responding. In fact, I felt the car speeding up. The patch was just about 10-15 ft wide; the moment we were over it, I felt the brakes respond.

- Eagleville, PA, USA

The car, a 2010 Prius, accelerates forward when going over a bump in the road or a pothole, as the brake is applied. The problem occurs at an unpredictable frequency. The consequences are that I lose control of the car's speed. I have reported this problem to my dealership several times since purchasing the Prius and they have found no problem, stating there is nothing to fix. I have been very concerned about the problem, even before the recent events in the news about Toyota. Had I known about this site, I would have registered the complaint earlier.

- Roslyn Heights, NY, USA

My 2010 Prius has sped up at least three times when I either drive through a pothole or cross railroad tracks, forcing me to hit the brakes hard. The brakes worked as they should and no accident resulted.

- Knoxville, TN, USA