Ive done the "open and close door" thing in cars before, but when theyre going just a few miles an hour, not 70!!
It does sound like this is not the whole story. Why open a car door at 70 mph, whatever your concern about the door. Surely you'd realise thats dangerous??
Well keep in mind they may not have actually been doing 70 MPH. It seems the speed involved is somewhat hear say:
“I asked what had gone on and was told he tried to open the car door and shut it again because it wasn’t shut properly and apparently fell out at 70mph
It wouldn't surprise me if they've just thrown in the 70mph bit because that's the speed limit on a motorway and it added to the overall story. So they may have been doing a slower speed at the time. His lack of serious injuries would suggest this too.
I can believe it happened. He's got into the car, not shut the door properly. They've got onto the motorway. Driver has finally lost patience with the beeping noise and told Michael to shut the door properly. He's opened it a little to close it again and it's blown open or something and he's tumbled out. Probably due to not wearing a seat belt. Maybe they were having a heated discussion about something and that's why they've ignored the beeping for so long or perhaps Michael makes a habit of not shutting car doors properly.