Portable global positioning system, or GPS, units that help drivers with directions are popular prizes for thieves, says Richard Ward, director of the Auto Claim Department at MetLife Auto & Home in Warwick, R.I. If an owner has one, Ward recommends removing this car part from plain view when the car is parked. It would cost about $150 to replace.

However, if the GPS attaches to the car with a suction cup, it will probably leave a residue ring on the vehicle when removed, he says. When thieves see that, they'll know that the odds are good a GPS unit is in the car.

The thief may break in the car to try to find the unit, even if it's not visible, says Ward. "The best thing to do is remove the GPS and then use an antibacterial wipe to get rid of any ring that's left behind," he says.

A stolen unit is added trouble for car owners if they input their home addresses in this car part, because it could give thieves another mark to target. Instead of entering a residence in the "home" section of a GPS, enter the address of a local business that's nearby, says Ward.