Your car, at 183mph, has to contend with cars operated by distracted
drivers, drivers at 57mph, drivers who are drunk, pedestrians throwing
rocks from bridges, drivers who are making ill-considered judgements
about weather conditions, etc.

Well of course it wouldn't be safe to do 183 mph on an existing motorway,
they just aren't designed for it as you say. But neither are most of our
railway tracks.

However, we could build some new high-speed motorways, suitably aligned for
183 mph, with a minimum speed limit of 150 mph or something, and it could
well work.

Of course, if you got a blowout at that speed the results could be rather
interesting.