Just thinking as far as bait. It needs to be visible to attract thieves. Any car will have a radio. What's eaiser to steal is a GPS or an iPod.
Of course you don't want to leave one in there BUT almost anything that has a WHITE charging cord maybe associated with an iPod, iPhone......so get a car charger that is white and plug in one end to the cigarette lighter/power source and DO NOT plug in anything but lead it to either under the seat or into a glove box/compartment to GIVE THE ILLUSION THAT THERE IS AN iPOD/iPhone left in the car....
I thought of this because when I was younger a friend had a pull out radio and off course the one time he put it under the seat it got stolen because the thieves assumed there was something under the seat of the pull out radio wasn't there.
But beware, as Matt B. alluded to anyone getting in to your car could cause damage...
Or you can just let the pit bull sleep in the car....