On 13/02/2019 16:54, Dave Plowman (News) wrote:
In article ,
Brian Gaff wrote:
Actually my neighbour had a Metro and boy could that thing move. The
speedo kind of just hit the end and after that it was guesswork. Only
problem with it was that it tended to be full of rust even when new.

As I said - a very optimistic speedo. Some makers today do just the same.
When making one which is within 1% accuracy should be child's play since
they are counting pulses.


Yes you could do it if the pulses were coming from a laser scanner
pointing at the road so wear and pressure changes in the tyres didn't
have any effect, or you could drag a fifth wheel speedo behind you to
get an accurate speed.