I like cats but I wouldn't want mine messing up my top.
My weapon of choice would be a paintball gun. It wouldn't kill it but it wouldn't go anywhere near the car again. Or you could try Sour Apple, it is a pet repellant, that smells awful. Pets avoid it like the plague, but I am not sure if I would rather have a smelly top or a cat on my top. A water gun would work too.
