My wife parked our 2007 Prius in the driveway tonight, which has a decent incline, but when I looked out the front window a half hour later the car had rolled into the street! She turned the power off before she got out of the car which should have automatically put it into park, and the car didn't move when she got out of the car. I'm going to bring it to the dealer tomorrow, but any ideas on what it could be? why the car would start rolling after it had been parked? Anyone had a similar problem? I've got it parked with the parking brake now, though it really shakes my trust in the car.