I'm wondering of there's a way to have a small amount of voltage course through the body- specifically the front fenders and maybe the hood, as that seems to be where everyone wants to touch the car to see what stainless steel feels like. I just recently washed and cleaned up the car, took it out to La Jolla today for a wedding rehearsal by the beach, and parked in an area where there didn't seem to be a lot of foot traffic (by the art museum), and not too many cars, only to come back and find lots of cars nearby, and lots of greasy fingerprints.
If I could get 9 volts - just enough to give a small jolt, along with some kind of recorded verbal warning (and maybe a window sticker), that could work.