speedometer repair.

[A G Wood]

Hi Malcolm, just as an aside we struck the same issue re perceived speedometer inaccuracy after the advent of GPS enabled devices, most memorably when one of the light truck [=utility/pickup] models went from a fully mechanical speedometer to an electronic analogue unit that read 10% high, despite the meeting the acknowledged industry/legal standard. Most of the customers were more concerned however with the likelihood of an odometer over read costing them in distance based road user charges... The discontent got bad enough that the local Service Engineers and the Factory Engineers got involved and the explanation offered to us peasants at the coal face was that the 'error' was deliberate to avoid potential liability in the case of an operator being pinged for speeding and it later turned out the the speedometer was indicating under. The odometer [being independently driven] was however spot-on. Eventually the most disgruntled users were offered a tweak of the speedometer electronics by an automotive instrument tech to bring it 'closer' to the GPS speed which seemed  to calm them down. Some doubters still had to be taken on a demonstration drive over the local surveyed 1000 metre speedometer test distance to convince them that the odometer was spot on though.