I wish developers could use the physics engine to flip the vehicle.

Suggestion:
If vehicle is not upright = correct position you get "spacebar" push action. what pushes the vehicle 45'Degree up, with some strenght. So you could easily upright a ATV vehicle.

But if you would want to upright a larger vehicle like a truck, you would need to have like 5 players to synchroneusly press the spacebar to swing the vehicle forth and back until you can upright the vehicle realistically.

I think the above would be good way to make game realistic and use the physics engine the game has ;)

Another good suggestion:
Add towing rope to all vehicles, and allow it to be attached at ANY point of the vehicle... so you can pull the vehicle to upright position with another vehicles help.