Why does it have to be a motorway? Indeed, why do we have to actually see the incident?
The big Tesco site on the edge of Ipswich has a car park where it's impossible to drive at more than about 10mph, even if you want to. So I'm still baffled as to how this happened on Sunday!
http://www.ipswichstar.co.uk/news/four_vehicle_crash_traps_two_inside_car_in_tesco_carpark_in_copdock_1_4382567
Similarly, I came out of the country's biggest Sainsbury's store some time ago and saw that one car had apparently:
(a) reversed into a space which was only just wide enough for the vehicle, with no room to open the doors ;
(b) continued reversing, presumably at considerable speed, straight through a bollard ;
(c) still continued reversing across a busy footpath and the next roadway on the car park ;
(d) slammed into the vehicle beyond that ;
(e) shunting that car into the one on the opposite bay ; and
(f) pushing the whole lot so far back that it had ended up in the parking space previously taken by the car it had hit!