In the summers, I used to put the cats out in the garage. A couple windows were out, so I put up chicken wire. That worked pretty well. Maybe you live in a milder area where there are no garages but just car ports.
It is your responsibility to keep the cat out of your neighbor's territory but still. If he values the car that much, there's plenty of other things that can happen to it if he doesn't keep it in a locked garage.
Kinda wonder how he keeps birds from crapping on the car.