You may recall my email of May 2010 when you advised me I could not reject a new vehicle for what I thought was a speedometer that over reads by 10 per cent. I have now received confirmation from the MD that Vauxhall sets its speedometers for the Astra at 10 per cent over, an answer Vauxhall avoided giving me for almost 12 months. Vauxhall is not alone in deliberately setting a speedometer to over-read, as is apparent when travelling in convoy in a 40/50mph restricted area or overtaking on a motorway with the driver in the middle sat on a true 63mph.

How many other measuring devises does one buy and have to accept a 10 per cent error rate? If we as drivers have to accept this do you agree it is surely incumbent on the manufacturers to advise us of their over-reads and let us make our own mind up how we drive. Not all cars are the same: a recent loan of an Agila had an over-read of 3mph through the range to 60mph, whilst my last car, a Vectra, had an over-read of only 2mph at 70mph