Dummy Car Alarms
More of a prevention than anything else, when a potential car thief approaches a car it has been proven statistically that they are 90% less likely to try to break in if they see some form of alarm displayed on the car. Dummy alarms usually have a red light, or appear as if the car has an alarm system, and in most cases this is enough to scare off any potential car thief.
Dummy Car Alarms, flashing dummy lights and fake alarm systems.