What is the best way to stop a car thief from stealing your car?

 

windows full up, doors locked, keep it in a garage or well lite area, car cover with lock, loud alarm, lo-jack. Just for your info, if a thief wants to steal your car, with all the above for security, it will be taken. make sure you have insurance.

 

Pittbull chained to it. seriously though Amech is right but if you are savy install a kill switch somewhere on the car that is not too obvious.

 

sell it that way you have no car to steal. if they really really want it they will find a way to get it like via tow truck while your shopping.