This happened to a driver in my center years back. CHP was in high speed chase and traffic ahead was stopped. Our driver was at the very tail end of the traffic, and the guy fleeing was insanely going to try to split lanes, didn't have the room, and plowed into the package car. Tipped it over on it's drivers side and he had the door open. This was one of the old 800's with just a lap belt and thankfully he had it on, but one of his legs ended up getting pinned between the package car and the road. Needless to say, he was out for quite some time, but thankfully made a full recovery. When I think back about driving with the door open with just a lap belt, it was kind of crazy, but I did it daily for more than a decade before the shoulder belts showed up. Probably not a whole lot safer with the shoulder belt either. But it was too damn hot to leave that door closed.