Hmm, I'm thinking along the lines of the Unibomber...
Load plastique into the columns on the interior, and wire it to the security alarm. If wires are cut, BOOM!
You'll loose the car, but that's one or two or three thieves who will never steal again!
One small problem - don't forget about it when it's time to change the battery LOL
Sorry it's 1am and I'm tired and I'm pissed that people target s*** like this.
LZ