Highly doubtful that the firearms came from an "unlocked car".
While I'm sure a goodly number of guns get stolen from home burglary, even more than from cars, here lately we see on the news, on a regular basis, some homeowner security cam vid of little bastards running around neighborhoods checking for unlocked cars. So and so place got hit by car burglaries and a gun/guns was stolen. Whereupon the TV will tell us we aint in Kansas no mo. Lock your car doors and don't leave your gun in your car when you go inside, they'll tell us. Trying to change who knows how many decades of people having a gun that lives in the car at all times.
Our guns stores had to harden their business's lately because, for a while, they were smash and grabbing gun stores...taken many guns at a time. That was a new phenomenon.
Times, they be a changing.