> Since truck, bus and train speedos can be accurate why can't they do
> the same for cars? It can't be hard in these days of electronic
> everything to have some optical revolution counter on an axle so whats
> the problem? I drove past one of these flash you speed up signs the
> other day and while my speedo said 38 the sign said 34 so thats a good
> percentage out. And my tyres and new and inflated to the correct
> pressure so they're not the culprit. So why don't car manufacturers
> bother?