We drive a 2010 Prius, purchased this fall. On three separate occasions, when I tried to brake in an area with some ice, the car accelerated rather than stopped. On two of the occasions, I failed to stop at an intersection (no one coming in the opposite direction) and on the third, the ice patch was about 3 ft in diameter on one side of the car only. I was going rather slowly, following a car that slowed for a speed bump. Luckily the other car accelerated and I did not hit it. The speed bump slowed me down and then the brakes started working.

- Emmaus, PA, USA

Prius braking problem when going slow speeds over a bump or pothole.

- La, CA, USA

I drive a 2010 Toyota Prius. On multiple occasions while attempting to slow down on rough surfaces, the brakes temporarily stopped working for 1-2 seconds even though the brake pedal was depressed. The most recent incident occurred while exiting the highway and attempting to slow down quickly on rough pavement. Luckily, there were no other cars in front of me or there would have been a collision. If a car had been in front of me on any of the occasions then there would have likely been a collision.

- Liberty Twp, OH, USA

The brakes on my 2010 Toyota Prius failed to engage while driving over a pothole. The car seemed to accelerate briefly but then the brakes kicked in once I hit the brake pedal again harder. This is the third incident of similar problems since I purchased the vehicle in July 2009.

- Tucson, AZ, USA

1. I was driving on a local road and was switching lanes. I pressed my brake pedal very slightly as I was crossing the lane divider and as I hit one of the plastic bumps, my car accelerated forward. 2. this has recurred many times and there were no vehicles in front of me everytime it happened so I was able to come to a stop. Several times I would either cross the pedestrian walkway at the intersection when this acceleration occurs. 3. I took my car to the dealer several times and everytime they told me it was normal and there was no problem. They were lying and completely clueless!!!

- San Jose, CA, USA

Applied brakes at a stop light. The Prius (purchased in July of 2009) ran over a bump, and it seemed like the brake disengaged. I removed my foot from the brake pedal and reapplied the brakes. The brakes seemed to engage and came to a stop.

- Walnut, CA, USA

I've owned my 2010 Toyota Prius for 5 months now and frequently (at least twice a month) experience problems when braking on uneven ground. When I am hitting the brakes and run over a pothole or sudden bump, the car stops slowing down and almost shoots forward (feels like I'm hydroplaning) for a split second then resumes braking. This happened most recently today and could have caused an accident if I were closer to the car in front of me when it occurred.

- Sandy, UT, USA

My 2010 toyata Prius (purchased in Sept. 2009) has had repeated problems while braking over a patch of road with small potholes. If the brakes are engaged while over the patch of uneven road, the car lurches or "jumps" over the spot on the road and the brakes don't begin to catch until the car gets over the patch. This has happened 5-10 time over the last four months at a stop light.

- West Greenwich, RI, USA

2010 Toyota Prius braking problem. I bought a 2010 Toyota Prius approx 4 months ago. During the approx 10000 miles I have put on the car, I have experienced a braking issue approx 5 to 6 times. Most times I was braking for a stop sign in a 30 mph zone. Once I was braking for a red light in a 45 mph zone. Each time, there was bumpy road during the braking, and the brakes released. I can't say if the car accelerated, or it just seemed that way because of the brake release. It did not cause any accidents, but once it was on a snow covered hill and I slid out into a 2 lane 50 mph highway. There was no traffic, and therefore no accident. Another time, I was stopping from 45 mph at a red light, and under braking, again on bumpy roads, the brakes released and I nearly hit the car in front of me. The brakes released enough allow me to panic and jam the brake pedal to the floor. The car stopped quickly.

- Vestal, NY, USA

Information redacted pursuant to the Freedom Of Information Act (FOIA), 5 U.S.C. 552(B)(6) I am a retired colonel, usaf, but continue to work for the af as a civilian attorney. I purchased a 2010 Toyota Prius hybrid, [xxx], on 9 Nov 09. Since that time, as recent as last evening when I pulled the vehicle into our garage, between my wife and I we have experienced on approximately six occasions the problem you have received other reports about concerning the vehicle's brakes. The "release" as I call it, occurred primarily when we hit irregular patches of roadway, such as potholes, washboard-type surfaces and the like. Last evening, as I mentioned, it actually occurred as I was entering the garage. I approached a little faster than usual and was braking as the front tires encountered the elevated cement beyond the base of the garage door. The braking action was lost just for a moment after the impact with the cement. It's not that the engine speeds up when it happens, it's the forward momentum of the vehicle that increases with loss of the braking action. That has been the case each time it has happened. In fairness to the dealership, I have not notified it yet because I read not too long after the first time this occurred that other owners were beginning to report this problem and that Toyota was developing a software fix for it. I assumed shortly there would be something in the nature of a recall and owners would be notified to bring their vehicles in for the modification. I do intend to notify the dealership tomorrow, but thought it necessary to report this to you now given the spotlight put on it today.

- Floresville, TX, USA

Our 2010 Prius sometimes lurches forward on hitting a bump or driving on rough terrain. This happens predictably at certain locations. Both my wife and I have observed this behavior, maybe a couple of times/week. Not certain whether it's momentary acceleration or loss of braking but we think it's loss of braking. We have not yet taken any corrective action. I read in the paper that Toyota is planning a recall.

- Bethesda, MD, USA

2010 Prius loses brake force when regenerative braking is used over potholes or other uneven surfaces. It appears that when wheel slip occurs when braking in such instances, the regenerative system is disengaged causing loss of braking until the friction brakes are engaged by depressing the brake pedal farther. This has occurred on multiple occasions and can be replicated.

- Ridgewood, NJ, USA

When the 2010 Toyota Prius goes over a pothole or over an ice patch is looses braking ability for one or two seconds. This has happened numerous times, the last time on the morning of February 3, 2010.

- Potomac, MD, USA

Braking problems with 2010 Toyota Prius. Since the purchase of this car on August 22, 2009, under the cash for clunkers program, my wife has repeatedly described the situation in which the brakes release unexpectedly. Specifically, when braking at low speeds while driving over a rail crossing (single track), the brakes release momentarily as the car experiences the bumping motion induced by the tracks. This can be replicated at will. In addition, she has noticed a similar momentary release of the brakes when approaching a stop sign on a slick road when the anti-lock brake mechanism was engaged. In these few cases, the car rolled past the stop sign and partially into the main travel way. Note this was not the result of sliding on slick pavement or the pulse-release of the anti-lock brake system but the release of brakes. None of these cases resulted in any physical impact or property damage--just the disconcerting feeling that the momentary loss of braking engendered. When my wife first noted this, I went to priuschat.com/, the Prius owners forum (which I think is sponsored by Toyota). The braking issue was noted by other forum members.

- Freeport, ME, USA

As I was going downhill, the road surface was uneven. I attempted to apply the brakes. The pedal went almost to the floor as if there was no brake fluid. The car continued to go forward as the brakes did not engage. As I pushed the brake pedal further, the brakes engaged.

- Syracsue, NY, USA

When driving I sometimes momentarily feel a pause in the braking system of my new Prius. This occurs every time I drive on a certain street at a fairly high speed. While I am braking my right front tire goes through a pothole while my front left tire remains on flat tarmac. As my front tire comes out of the pothole I feel as if the brakes stop working for half a second and then they start working again. I estimate that I am driving through the pothole around 20-30 miles an hour. I drive this way every day from my work to house and I am always braking on this stretch of road as I turn a corner right after the pothole. There is a traffic light right after the pothole so whenever the light is green as I approach the pothole this happens to me. This has happened to me around 50 times - ever since I bought my new Prius in September 2009.

- Princeton, NJ, USA

2010 Prius brake applied in zero temperature weather approaching a red light on slight down sloping road covered in ice/snow. The brake pedal was pushed as would normally be applied (maybe approx 1/3 - 1/2 brake pedal travel) and there was no applied braking. The car kept rolling forward to where I had to make a decision to continue rolling with a right turn into the intersection and continue travel. Luckily the oncoming traffic was far enough away to not crash into me. I would estimate that the brake was applied for about 1-2 seconds, enough travel time to force me to make a decision that I needed to continue through the intersection before the oncoming traffic. This same type of scenario occurred on an exit off of an interstate ramp down another down slope with ice/snow that again when the brakes where applied, the regenerative engine brake applied, but when the ABS went to engage due to the slippery surface, there was a 1-2 second duration of sensation of no brakes. Pushing pedal further (or just waiting the 1-2 second delay) seemed to eventually apply brakes. I am a systems/test engineer that performs numerous work on commercial and military aircraft and I now know how to anticipate this situation for myself (I.e., I am more careful on braking earlier especially on slippery surfaces more than normal distance from my other Honda vehicles on same type of surfaces to account for this possible 1-2 delay time in braking); however, this is unacceptable for my wife who does not have the same experience as I do or same technical feeling of what this vehicle is doing. Again, if the traffic on that one intersection was closer to me than it was, there would have been a side impact collision. I have yet to experience this issue on solid roads over bumpy surfaces. With today's Toyota revelation that the Jan 2010 Prius has a fix for this, I demand to have this same fix applied to my three month old 2010 Prius.

- Cedar Rapids, IA, USA

I own a 2010 Prius, purchased 7/22/09. I have experienced a sudden surge when traveling over a bump or large pothole. The car momentarily surges and feels slightly out of control. This has happened about a dozen times in the 6 months I have owned the vehicle. I am concerned about my safety and this is why I am writing to you.

- San Marino, CA, USA

My 2010 Prius accelerates over bumpy road conditions irrespective of whether or not my foot is on the brake or not on anything at all.

- Calabasas, CA, 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