An unlocked vehicle with a key in the ignition is an open invitation to any thief, regardless of which anti-theft device you use. A visible or audible device alerts thieves that your vehicle is protected before they attempt to steal it. According to a recent study by the NICB, users of steering wheel locks were four times less likely to become a vehicle theft victim than the average motorists. Some second layer devices are also effective in protecting your vehicle from burglary and vandalism. Electronic immobilizing devices prevent thieves from bypassing your ignition and hot wiring the vehicle.
Some devices have computer chips in ignition keys.
Other manual devices inhibit the flow of electricity or fuel to the engine until a hidden switch is activated. A third category passively immobilizes the vehicle by interrupting the starter, ignition and fuel. Device A tracking system emits a signal to police or monitoring service when the vehicle is reported stolen. Tracking systems are very effective in helping authorities recover stolen vehicles.