In the 1946 edition of the highway code stopping distances were first included, since then they have remained UNCHANGED (except for metrification!
As the test were carried out just after the second world war ended the tests must have been carried out on cars manufactured before and just after the war. So probably on cars manufactured around 60 years ago.
I now drive a car with vastly better electronic assisted suspension, tyres twice the width, Disc brakes with power assistance and electronic emergency system with anti lock brakes.
Also new technology high grip road surfaces are common.
Do you think the highway code might need updating?
I imagine the distances are based on the worst possible scenario. Not all cars have anti-lock and 19"tyres. So they err on the side of caution. After all,it's just a question,common sense is a much safer judge of breaking distances in relation to your speed than numbers on a paper
I agree, toureman, that the figures are probably way out of line with current performance. I remember non-power, drum brakes - lock the wheels? Ha! Only on wet or snowy roads!
But why bother changing them? They have no relevance to modern motoring, and once you've passed your test, whoever remembers them or needs them ever again? As R'n'R says, you just use experience, not the numbers.