Steve Gibson mentioned this in Security Now (episode 508 http://twit.tv/show/security-now/508 ) . The basic hack involves most any car where the door unlocks as you walk up to the car, or touch the door handle (but not the ones where you push a button). The bad guy is near the car with a RF amplifier which boosts the signal coming from the car so that the key fob can hear it at a distance of up to 100 meters. Since the car thinks this is a legit signal, it gets a real code from the fob and doors open. This seems to affect all makes and models. If the car can be started remotely is unclean and may vary with mfg.
The only protection for this is to be more than 100 meters away of to wrap your fob in aluminum foil or a RF blocking bag (such as used for passports and RFID). Silver/plastic anti-static bags do not work, the bag must be high conductivity.