I Park on a hill and pull the handbrake up as far as I can, I usually point the tires to the curb or leave the car in gear, however last night I didnt. I woke up this morning to my car sitting against the back of the car infront as it has rolled about 5 meters down the hill. Why would the handbrake fail like this? Luckily it looks like only a small scratch and a smashed number plate :/.