I fill my car with rattle snakes any time I park it outside of my garage. It takes a few extra minutes out of my day but my miata has never been stolen.

 

wire a switch in between the fuel pump and the battery. The car will crank but they will go nowhere! :]

 

Strobe Light Convert your interior dome light to a strobe light that activates when the thief opens the door. In addition to the sound of the alarm, the strobe light will make your car more visible in crowded areas such as mall parking lots, enabling law enforcement and security personnel to find it more quickly.

Interior Alarm Install an alarm in the car's interior. A piercing, high-decibel alarm blaring in the ear of thieves may ward off the theft attempt or discourage them from driving the vehicle for a long period of time.

Fuel Pump Disconnection If your car has an electric fuel pump, connect the fuel line to the alarm system so that fuel pump won't function when the alarm system is activated. Even if the thief disarms the alarm system, the vehicle engine won't receive any fuel and fail to start.

GPS Tracking Install a GPS tracking system in your car. By installing a GPS tracking system, the location of your vehicle can be quickly determined by the system provider who will alert law enforcement that your car has been stolen and where it is.

Silent Alarm Most of us have experienced the annoyance of a car alarm that goes off due to a random vibration and not a theft attempt. A silent alarm alerts only you and not the rest of the world that the alarm has been activated. A signal is sent to a transmitter that you have in your possession, allowing you to investigate the situation promptly.