Oddly, I work for a communications company selling systems just like that. It's not too expensive, and can be relatively easily fitted. I haven't heard of it being fitted to a vehicle before, as it is mainly for door access of some description, but I imagine it could be done. Thinking about it, dont some high end cars come with something similar, keyless locks and remote control boots etc? Possibly a daft question, but why are the sat nav screens even detachable? Can they not be built in like the rest of the system in the dash?