All depends where you live and what car you drive.
If you have a Subaru Impreza..'the chances are it will be used as a get away car'...i was told by the sales rep in the Subaru garage when i looked at one. If you have a standard basic 1.0 Metro you could probably leave it unlocked and no-one will touch it.
If the car is more than half decent, or worth some value, i would go for a wheel clamp when it is at home, & a thatcham 1 alarm.
You can get a bollard for the driveway to stop it being driven off, but if your car was in the garage, and the bollard was up, people would start to think what you had in the garage for you too put the bollard up...
A guy i know had a CBR900RR (Fireblade) back in 1998. He parked it at the back of his garage, then parked the car up too it so you could not get it out. He then parked another car against the door to the garage. This was how he did it for months.
One morning he got a knock from the police because his car was in the middle of the road. When he went outside, his car was on the road, and the garage door open.
Turns out the theifs had cut the brake cable on the car to roll it away from the door. Opened the door, but could not start the car, nor move it to gain access to the bike. So they dragged the bike over the top of the car.
Imagine the insurance claim for that...the loss of the bike, and the damage too 2 cars..
If they want it, they will take it. I would prefer them to make as little mess as they could and never see it again.
This applies to my car and my bike..