You are right but now a days Vehicle GPS tracker are dirt cheap as low as Rs.6000; These are personal gps means you can install them yourself if you have a knowledge of DC Circuits and Relays. And you can track it yourself using your Android PHone, You can Lock/ Un-Lock Doors, Turn Off engines, Ignitions, Geo Fencing and real time tracking etc.
I have used android phone tracking thingy but it needs internet i dont know how it will work without sim and internet. Plus u can just track not turn off or door unlock etc.