You can't make a car impossible to steal, if someone wants it then they'll take it no matter what,

Not sure if it was on here or another site but there was a car that was parked in a big warehouse with other cars and caravans etc surrounding it with big locked doors and all that...

The car was still taken by thieves, all the other motors were parked outside the workshop the following morning


Can make it harder for thieves but never impossible