Back when I had my Mad Max cars from Australia, I had to get a lot of props and parts from Japan due to the HUGE fan base there.....where I found this wonderful product!
Its called Black Cat Scat. And it works very, very well. After ordering it, I figured out how to make my own. You will see what I mean after you google it. A water bottle with legs and a cat face, with glittery eyes, that screws onto the bottle placed under the car and they really wont go near it. They think its another cat in the dark.....sounds stupid, but no stupider than cats, as their brains are the size of a walnut, so yeah, lol, it's a simple and effective solution to a problem that's been over thought. Cats wont go where another cat is at, they don't know. When they do their staredown, with glitter eyes they lose to the water bottle and move on....
There is also another Japanese item that works with chemicals. It comes in a pellet form that you spread around and keeps em away....supposed to smell horrific to cats. Both can be found easily enough online.
Yeah, nothing else works by the way, cept dogs. Which is another problem. Hope this helped you.