I onced managed an indicated 143mph in a Nissan 200SX Turbo (European - shape of the 240SX i the USA) and it was 'suprising' how fast the road went by and how early you had to start braking for the roundabouts (traffic circles).
I think the old boy in the Metro was quite suprised when I passed him too.
There is, in my opinion, a noticable step as you pass 100mph, and another over about 130mph. I just can't imagine 250mph!
Of course that sort of speed is completely irresponsible on a public road.
