Seems a valid question to me. A popular tactic at most boat ramps around here is to take anything valuable out and leave the doors unlocked, at least that way you don't have to replace a window; of course then you run the risk of the thief being pi***ed that there wasn't anything for them to steal in which case they may just trash the car anyways. I just drive an unassuming car that most people consider hideous (Honda Element) and hope for the best, so far I've had no issues (knock on wood).