my folks insurance agent said a dog is probably the best deterent.
my friend left his rottie in his car while he was @ the dr some one tried to reach in the sunroof and take the sterio. they left their watch behind. I had 2 of the sons from that dog. never had to worry about being robbed with those two around. most defensive and loyal dogs i've ever had. They were not all bark and no bite like other dogs i've had, but they were totally cool with people if i said they were ok. couldn't give them regular dog toys though they were a waste of $, they chewed on tires instead.