There's alarms that don't make a sound,but they page you when your ride is tampered with. This gives you a chance to not only prevent your rig from being stolen,but to catch the thief in the act,thus stopping others from having THEIR vehicles stolen by that thief as well. One less car thief on the streets.

You then have the option of handing the car thief over to the authorities or feeding him to the fishes or worms...
Speed