On Tuesday, September 29, 2015 at 1:26:18 PM UTC+1, Dave Plowman (News) wrote:
In article ,
brightside S9 wrote:

Manufacturers will normally deliberately calibrate their speedos to
read 'high' by some amount between 100% and 110% to keep themselves
within the law.

It also means the car shows a higher top speed than reality. Better MPG.
And needs servicing more frequently. So a win win win for the makers.

In these days of pulse counting speedos, there is no need for the same
sort of tolerance as once. Only thing which will effect the reading is
tyre wear - which makes it read on the 'safe' side anyway.

--
If your sat nav indicates speed, it is interesting to see the difference between that and the car speedo.
Simon.