Parked:

Once you hop in it slowly closes, and of the delay and youre off to go. I know of a mod that when you go in a vehicle, the view hatch slowly opens.
This is a suggestion for aircraft and attack helicopters. I dont know about land vehicles and other stuff i didn't mention it would look silly having a parked car with its doors all open. It makes more sense for the helis and planes..
I think its possible to do it since the EOD huey medivac door closes while in the air.








