Volvo Gave Away the Most Important Design They Ever Patented
Seat belts work. I once spent several minutes held upside down by one, after the car I was riding in rolled onto it's roof.  Everything loose in the car ended up on the headliner -- change, jackets, crusty old french fry bits...BTW: You are almost certainly not strong enough to support yourself by one hand while you unbuckle.  But falling down to the roof after the wreck is far better than being thrown from the car during the wreck.