this guy sounds like a real asshead. just ask him wtf is up with this. generally, rational people will respond to calm, collected questions. Like "Hey, I noticed dings on my car, my friend's car and my friend's girlfriend's car that definitely came from yours. Could you be a little more careful?"

If he gets out of line, just put in a call to the police and let them sort it out. Then whenever you move... vandalize!!