Why use redundant methods when latest technology is there to aid you. Give the old car alarms a miss and adopt the GPS Snitch instead. The device uses GPS, cellular technology, and the Web to help you locate your car. All you need to do is attach it to a 12 volt power point in your car and with its motion detector and cell connection; it can send you a text message when it feels your car being moved. And when you want to find your car all you need to do is hook it up to the net and locate it on the map or send a text message request. If you send a text message request, the system will send you a text reply with the car's location.

The hardware of the GPS Snitch costs $399, and the required subscription plans start at $14.99 a month or $169.99 per year.

Source