
Originally Posted by
ericbalajadia
The only way for someone who may be having your key now (assuming that someone has it already) to use it on your car is that if he had followed you secretly until you got home, wait until after you retire, enter the premises, open the gates from the inside and there, steal it. If parked outside, the better. If he doesn't want to trespass, he can always wait in the morning of any day, follow you for when you may park the car somewhere outside, then steal. Chances of that happening are very remote and far-fetched but strictly technicaly possible.
If you really want that possibility avoided, you can ask the dealer to change the entire immobilizer/anti-theft system, the ignition and all door locks with a set of new keys.