Two problems related to power train driveline have been reported for the 2007 Toyota Prius. The most recently reported issues are listed below.
While parked with the car turned on, the engine engages to run the a/c or heater and the car lurches forward. The display screen will sometimes display a warning that there is a problem with the park mechanism and that the car should be shut off and parked on a level surface with the parking brake engaged. My research has led to the park lock mechanism. Toyota says that the lurch is normal and due to wear on the park lock. The "fix" is to use the parking brake. What if you forget or aren't aware of this? what if the park lock fails and the brake isn't on? none of these is unreasonable to expect. The potential is for the car to move on its own, even with no one present in the car or in the driver's seat. This is an inherently unsafe design and should be pulled from the road.
Several near miss incidents due to no acceleration on slippery surfaces - wheels do not even spin to no traction is even possible. This is especially so when pulling into traffic on snowy days. Simply unable to get out of the way of oncoming traffic. Toyota dealer tells me "this is normal. " I am 63 and of all the vehicles I have owned, this Prius is the only one with this problem. I could be dead, or someone else could be dead.