Personally, I'd go for a shaped charge of C-4 with a 1-minute delay fuse under the driver's seat, aimed at the thief's testicles. Just be VERY sure to disable the trigger system when you drive it yourself!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!