I know it uses the car sensors for throttle, brake and steering, but are we sure it uses the cars GPS signal? Is the car's GPS better or worse than the phones? If it's using the phone's you would want to mount the phone on the windshield for better line of sight for the signal, but that would mean a cord running into the center console.
Current: '13 E92 M3 Euro Delivery
Wife's: E39 M5, E36 M3
Gone: E86 M Coupe; E30 M3