The Model S is almost impossible to steal. The thief would need to have the key fob in their pocket. Even if they managed to get into the car, there is no switch to break, no wires for being able to hotwire the car since the authentication is done over CAN, and it has an immobilizer.
With having an app that can track the car, they'd have to have intimate knowledge of the car's inner workings in order to even think of messing with it. (not to mention at least a week plugged into the CAN busses.)
In my point of view, it is cost prohibitive. A thief would rather target a Honda or Toyota than Model S.
(BTW this has been documented in a white paper submitted by TM to an agency, I think it might have been the NHTSA.)
(Docket# NHTSA–2011–0174)