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??
And surely you'd realise the door was semi-open long before
you actually got on the motorway, because the range rover's alarm would be driving you mad?
The whole thing is bizarre and there's something odd about all this, IMO.