It's less about the cars, more about peoples concentration and awareness whilst driving. A sole driver paying full attention driving smoothly and allowing adequate space at 90 mph is far less of a risk than somebody half asleep at 58mph in the slow lane or a parent very heavily distracted by kids in the back.
I once had to break from speed in the outside lane with a good controlled firm and progressive breaking maneuver for stationary traffic from 90mph, with the obvious check in the rear view mirror to see the mum in the Picasso playing with something in the back seat for the child. I decided to tuck into the barrier and watch as she slid up the inside all locked up after her brown trouser realization moment.
