Trust me. With children and animals, I will never own a car worth battling a Mexican Cartel over ;)
So then OnStar is different than LoJack? OnStar is GPS and hackable:
http://members.cox.net/onstar/
First generation OnStar is based on a 3-watt Motorola AMPS (analog) cellphone, a Motorola embedded GPS and an embedded CPU with an interface to the vehicle bus (to unlock doors). The user or the OnStar agent can initiate contact with the cellphone. While the analog call is up, the agent can interrogate the current car location. If the car is in a location that has no view of the sky, the OnStar unit will transmit the last good fix before it lost view of the sky. That is usually good enough to find a car stashed in a garage.
OnStar also includes an airbag deployment sensor that automatically calls an OnStar agent if you get into an accident. The GPS query assists OnStar in sending emergency responders to the scene of an accident.