All my expensive cars are in my secured garage with alarm and security will be automatically called if the alarm goes off. And all my cars have class 4 alarm which means it has a GPS locator in it. I can see where my car is online so if it gets stolen and transported to East-Europe, I can follow it
I also get a call from the car-alarm company if something happens with my cars (alarm goes off, dead battery etc). The membership of the car-alarm is like 30 bucks per car per month but it's worth it in my opinion.