I used to do a lot of backpacking in the NC mountains. A a couple of the trailheads, cars were getting broken into. We almost always had a two or three hour trip there... with accompanied eating and drinking. When we get to our destination, we leave all that trash from the ride strewn about the vehicle with the doors unlocked (if they are going to break your windows, you might as well leave the doors unlocked!). We could even leave valuables in the vehicle, hidden, and the trash would cause people to skip it and move on!
My buddy had a rusty red 3 cylinder Saab in NYC. We parked one day near the United Nations building in the late 60's, and I locked my door. He said, "no, you don't do that in the City!"
Stig