On a personal note this was due to in the late 50's as a 7-9 year old in Scotland I well remember Grandads car had a bench front seat with no seat belts and there was a road we used where if Grandad gunned it right the hump back switchback (think Nessie humps) would simulate weightlessness. As a child it was called the 'whee' road. Don't think it did the springs much good