Car was in motion about 20mph. When brakes was applied, the car failed to slow down but instead quickly accelerated. Continuously applying the brakes did nothing. Car came to a stop apply running into another car.

- Nokesville, VA, USA

Brakes failing when applied hard or while driving over bumps.

- Austin, TX, USA

The Prius has a problem when braking over broken pavement or potholes. This happens when the brakes are applied to slow the vehicle and the car enters an area of the road where there is uneven ground. The brakes seem to not work for a second even if there is steady pressure applied to the brake pedal. This problem causes quite a startle to the car's driver. This is especially a concern to us when this happens at a crosswalk. This is an ongoing problem. Toyota of America has been contacted twice, I have taken the vehicle in to my local dealership but no fix is available.

- Old Town, ME, USA

When braking while the vehicle is going over a bump or depression in the ground, the vehicle lurches forward. Instead of stopping the vehicle seems to accelerate forward. This happens consistently in this setting.

- Niles, MI, USA

The contact owns a 2011 Toyota Prius. While the vehicle was stationary, all of the warning lights illuminated on the instrument panel. The vehicle was towed to a dealer where it was diagnosed that the brake master assembly and the brake booster needed to be replaced. The manufacturer was made aware of the issue. The failure mileage was 81,000.

- Garden Grove, CA, USA

Brakes disengage momentarily when braking on a bumpy roadway. I have had this happen multiple times. It feels like the ABS system releases the brakes and then reapplies braking. Luckily, I have not had vehicles in front of me.

- Saint Albans, WV, USA

Every once in a while - it can be months between events - our Prius momentarily slams on the brakes when driving at highway speeds while nothing else is going on. We know it's not operator error. It's happened to my wife several times and me once. When it happened to me I was driving straight ahead on a dry, lightly traveled divided highway during the day. Everything on the dashboard lights up, alarms go off, the car decelerates like I suddenly stomped on the brake pedal though my foot never moved off of the gas, it lasts for maybe a second and then the car is back to normal. It's the same each time it's happened. Luckily each time this has happened we haven't had anyone tailgating us. We've taken it to the dealer multiple times. The first couple of times they looked at us like we were loony. They checked it out and we got it back with a message that said the technician checked the computer and test drove it for 20 miles and the car was operating as designed. Except it happened again. We finally convinced them that this was maybe a legitimate issue and they said they brought in a Toyota field specialist who checked the car out and they said that the issue was the pcs wave radar sensor that was slightly out of alignment due to body damage (my wife had hit a small deer about a year prior to that - damage was minor and repaired at a local body shop). After they realigned the sensor, the car behaved itself for about five months. Until yesterday when it happened again.

- Woodstock, MD, USA

While driving and braking on a bumpy road surface, the brakes will initially work, quit working momentarily, then reengage. This happens regularly. I just took it to the Toyota dealership, and they say the brakes are fine and there is no problem. There was a Toyota recall for this issue on 2010 models. I'm afraid this issue will cause an accident. How can I get Toyota to address the problem?

- Mahomet, IL, USA

The contact owns a 2011 Toyota Prius. While driving at various speeds, the vehicle hesitated to decelerate without warning. The contact stated that the brake pedal traveled to the floorboard. The contact stated that the brakes needed to be pumped in order to stop the vehicle. The vehicle was taken to the dealer where it was diagnosed that the brake cylinder assembly needed to be repaired. The vehicle was repaired. The manufacturer was made aware of the failure. The failure mileage was 59,000.

- Nevarre, FL, USA

I was moving forward in a turn lane on a city street preparing to make a left turn. A vehicle cut in front of my car and it was necessary to make a quick stop to avoid an accident. Immediately red warning lights lit up indicating a problem with the brakes. The repair statement from the dealer indicated that the brake booster with master cylinder assembly had failed and needed to be replaced. The repair required over two weeks to complete and I was informed that the procedure in the service manual for repairing the problem was incorrect.

- Charlotte, NC, USA

The contact owns a 2011 Toyota Prius. While attempting to park, the driver depressed the brake pedal and suddenly the vehicle accelerated forward and crashed into a pole. During the crash, the front end sustained significant damage. The air bags did not deploy. No injuries were reported and a police report was filed. The vehicle was destroyed. The manufacturer was not notified of the failure. The failure mileage was 21,000.

- Walnut Creek, CA, USA

On at least six occasions, I have lost control for a second or two while braking. While applying the brakes, and simultaneously crossing any sort of uneven terrain, the vehicle suddenly darted forward as I slowed. After reading a large number of similar incidents via a web search, I decided I needed to report this possibly dangerous issue.

- Evanston, IL, USA

While pressing the brake pedal in a bumpy road, I feel the car accelerates and try to jump and I usually press the brake hard to stop. I have been experiencing this several times but never report. To clarify more, it happens while pressing the brake.

- Hyayysville, MD, USA

There are 3 issues I am having with this Prius. The brakes are the first problem. As others have stated, I too have the same lurching forward when braking over bumby or rough roads. This has been ongoing over the last few years. Second, the suspension is creaking and crunching when making turns at low speeds under 20mph. This happens when the wheels are turned all the way right and all the way left. This crunching noise happens when backing out of the driveway, making U-turns, coming to a stop on an incline, and braking over speed bumps. I've had the dealer look at this for the last year when I come in for service and one tech says they can't figure it out, another tech says he hears it but can't find the root of the problem, the service mgr. Also went on a drive with me and reproduces the noise concern but the techs couldn't find it. Most were suggesting new front suspension components-struts, towers, links, etc. I replaced the two front struts and all of the extra components-the noise concern is still there. I am very upset about this. Third issue is the ice-motor. When stopped at a red light and the engine shuts off, the car lurches forward and makes a creaking sound. It's appears that something is not right. The engine seems like it is loose. The engine also makes rattling sound when cruising lightly at 15-25 mph with the accelerator pressed slightly. The sound is coming from the passenger side, under the dashboard-glove compartment area. This is a rattle sound coming from the engine. I've had this looked at as well and the dealer states they cannot duplicate it. I have recorded all sounds related to these concerns and am taking it back to the dealer this month.

- West Hollywood, CA, USA

Just want to add to the list of complaints about this car lunging forward when the brakes are applied, primarily when the car is driving over rough terrain but not always. It is always unexpected. I've had to change the way I drive, but I'm not always sure I could stop it in every circumstance. I've taken the car in to a Toyota service center twice to look at it. They either can't get it to happen while they have the car or they say it's normal. It's not normal for any car I've ever had in twenty plus years of driving. It has only gotten worse and more frequent over the course of the three years that I've had the car.

- River Ridge, LA, USA

Traction control and ABS warning lights came on. Cruise control stopped working. Took it to Toyota who said codes indicated failure of master cylinder. Cost of repair $3,400. I think they have a defective part problem.

- Santa Fe, NM, USA

The vehicle was parked in a typical supermarket parking lot during a normal sunny day. The vehicle starts normally as the brakes are depressed. After putting the car in reverse, the brake pedal pushed back as the vehicle starts to back up. The brake felt very stiff and would not depress until the foot is lifted and re-stepped on it. It has happened about a dozen times in the last 3.5 years, no specific place or time. Was not able to be duplicated at the dealerships. The dealer said it's safety feature when you step on the brakes too hard, it locks up as in a hand brake. However, the lockup I experienced is different and only happens occasionally during reverse where the brakes is not stopping the car from moving. Seems to occur more often on sloped surfaces than flat, but cannot duplicate as it happens randomly, usually with multiple passengers in the car. This can be a real safety hazard if some one is behind the vehicle.

- Temple City, CA, USA

My wife was driving our 2011 Prius during stop and go traffic. She said the car just took off on her on it's own she tried to brake but it wouldn't stop. It crashed into the motorhome that I was driving. The air bags never deployed. The car was totaled due to the extensive damage.

- Arlington, WA, USA

This has happened multiple times since I purchased this vehicle. The first time this happened was at 2,500 miles. While applying brakes on a rough road or when crossing a pot hole, cracked road, or bridge joint the brakes fail momentarily allowing the car to lurch forward. It his happens regardless of the speed. I could be traveling at 15 or 50 mph and the brakes will fail and lurch forward. I purchased the Prius new in 2011 and have told the service folks at Toyota about the problem and they look at the vehicle and are not able to find a reason for this brake failure. This is dangerous. I have to make sure I start braking a good distance from a car in front of me as I am afraid this defect will cause an accident. If I have to brake suddenly and am driving over any road that is not smooth my brakes fail and lurch forward. How many people need to get injured or die before Toyota fixes this defect?

- Madison, WI, USA

We have been experiencing braking abnormalities for 1-2 months, and when our brake malfunction light came on we had it checked out. Initially, about 1 month ago, the Toyota dealer's service dept. Could not detect an issue, so simply reset the computer. But, again, the malfunction light returned and again, we returned the car to the service dept. On this occasion, they told us that nitrogen gas has leaked from the accumulator into the braking system. Research indicates that this is a similar problem experienced by 2010 Prius owners. We would love for Toyota to fix this issue rather than us cover the $5000 for brake system replacement.

- Denver, CO, USA