I have similar problem as yours. My solution is : put several dolls (animal shaped, e.g. dog, should be scary enough) on the car's area where they usually come and sit (on my case, it's on the front part, above the machine's cap, I'm not sure what it's called in English).
So far it's effective to keep the cats away.
p.s. the drawback is, my neighbor usually laugh when passing and seeing this.