The Topic: Cat prints

Random Usenet readers I've polled suggest the automatic 'scarecrow' which seems to be a motion-sensing hose attachment, of all things.

However, if $80 is a bit out of your price range, perhaps you could simply grease your automobile so that the cat finds itself unable to walk across it at all. Granted, it may be difficult to clean, but I'm willing to wager that any number of television programs would pay handsomely for a videotape of the trick in action.