I have found one of the neighborhood cats sleeping on my car top a few times (lot of carports rather than garages here in Phoenix) I keep 2 sheets of aluminum foil folded up next to my car which i unfold whenever parked and weigh them down with a couple of magazines across the top. I heard a while back that cats don't like the aluminum foil texture and won't touch on it
Seems to be working great, I haven't seen one of them on there since. I think they are somewhat trained now too as I haven't seen them on there even if I forget to put the foil on.
Let me know if anyone else has luck with this because my girlfriend thinks I am crazy.
