I guess I am getting old, my first thought is "my efficiency would suck". Still I wonder how a speed considerably higher than the highest speed limits I could f

I guess I am getting old, my first thought is "my efficiency would suck". Still I wonder how a speed considerably higher than the highest speed limits I could find in a google search was determined. Is there particular energy threshold for impact they were looking at? I am not sure that speed is survivable in any front end or offset crash with current technology but a crash where the car spins of control and doesn't impact anything won't much care unless the speed they picked is at the threshold for the average car to lose total control at.