I've at times thought about a canister of tear gas or pepper spray that was activated thru an alarm system when the car was started without the alarm deactivated. My buddy Rick takes his 90 pound Shephard with him when he takes the car out for an overnight---"Cupcake" really likes to sleep in the car... Would be fun to sit back and watch someone open the door on his car!!! Also like the Lojack idea, but I understand it's coverage area is limited???