I knew someone would say this, that is just something that had happened to someone. In that case if he has legged it out the door to steal my car I'm going to grab my bat, lock my door & call the cops. For the average dumb sh*t thief, they would break in, steal your sh*t, grab your keys if they can find them without waking you up. If they then goto steal it and realise it won't start, I doubt he's coming back into wake me... if it means someone may get hurt I'll give the code and let him steal it and get insurance.. but for the more likely scenario's I think an immobilizer is a good option.