It would useful to let the user nominate to apply a delay when the car is turned off before the unit shuts down.
Eg Rather than shutdown immediately when the car is turned off, the unit will remain alive/sleep mode (with screen off) for X minutes before shutting down completely.
This will assist users who are only stopping their car for a few minutes eg dropping kids are school, filling up with petrol and avoid the need for the unit to completely turn off then boot up from cold a few mins later.