The cat will only get his claws out and scratch his car if the cat is unduly scared or surprised-you really should politely advise this guy that with such an expensive car maybe it should be in a garage) Or if you really are concerned then watch your cat for when he sits on the car and give him a gentle squirt with water(tell the guy 1st, so he knows it's only water) or don't say anything and if you "accidentally" get the guy..Well added bonus for Elvis Sounds like Elvis has good taste