Still a non-tech description: Obviously, there is a "tracking system" needed that includes the GPS unit with cell phone in the car and a home PC with the related tracking software and a modem. The system's cell phone is programmed to call your modem at home and give it the GPS data in digital form. Probably, the home PC can intiate the call and request data, I dunno. That makes more sense. The tracking software on your PC then grabs the data and translates it into human-usable data in the form of a location shown on a map for the car you're tracking. If you're getting at how you can do this with your M-B, I'm sure you can't. You need to have a tracking system installed.

I think M-B has a tracking system, though, that works like OnStar. OnStar uses a GPS unit and cell phone to offer concierge services and emergency services notification. You can call an OnStar rep and just talk. You can ask for directions for the nearest restaurant. If the car's air bag deploys, it calls to notify them and they call emergency services in your area. The system gives GPS data when contact is made, so OnStar reps know where you are. If you lock the keys in your car, you can also call OnStar on your cell phone or from a phone booth and get the doors unlocked. Stuff like that.

A certain Polak may come on here and say that cell phone coverage isn't 100%. We already know that, but he likes to interject irrelevant info. It makes him feel real important. GPS signals are also not 100% reliable. When you drive in tight mountain canyons or in cities with tall buildings, you're likely to lose the cell phone signal and the GPS signal (just like you do with metallic window tint). Certain GPS units overcome this with "dead reckoning" and by using a ground-based GPS supplementary system called WAAS, but although this greatly improves reliability, it isn't 100% either. And, WAAS is available only in larger cities.