Project Idea: BTLE proximity automation (unlock/lock/start/stop)

I’m looking to leverage the M2 and BTLE XBee to enable car automation starting w/ relatively simple lock/unlock based on iPhone/Android proximity. Initially this would be for my Subaru and my wife’s Nissan with automatic car detection.

Future possible additions could be window/sunroof lower/raise from phone keypress, trunk unlock, remote start (after door opens), etc.