Just be mindful of the range, 1500ft is under ideal conditions (a straight unobstructed line from transmitter to receiver). Any obstructions like other cars, walls, bushes, etc. will all cut down that distance. The best systems are ones that use the cell network to send you a message like the previously mentioned lojack with the early warning system. It can email, page, text, and call you a friend or relative.
The onion is a humor website, but its just there to show that no one cares when a car alarm goes off even people with car alarms. If you're in a store, and an alarm goes off in the parking lot outside, do you immediately think it's your car and come rushing out?
http://www.transalt.org/files/newsro...rms/report.pdf