I could be wrong but your version should be those type with proximity sensor such that as long as the key fob is within a certain distance, you can open the door and keyless start the engine. Even if you leave the vincity, the engine will still be left on, as the system only has proximity UNLOCK and keyless start, but not the other way round. Probably your dad forgot and did not even lock the car after he left. (quiet engine!!)
I believe there was 1 older version of 7 series fitted with the proximity card system such that it works similarly but once the distance between the card and car is too far, the engine will shut off (to prevent theft).
Not too sure about the latest models/gadgets. You might want to try PML or the site sponsors (those that major in BMW accessories) for this option.
good luck