Reply from Vauxhall on this subject: Thank you for your email received on 9 March 2015 regarding your Vauxhall Corsa.
I have discussed your case with the Corsa Brand Manager and our Design Department, they have advised that are many factors that go into the design of a vehicle, which are taken into account by our engineers. When designs are at the blueprint and computer design stage, the designers have to meet a compromise between vehicle ergonomics and all the technical aspects.
In the case of a speedometer manufactured for sale in any Member State where imperial units of measurement are used, the speedometer shall be marked both in km/h and in mph (miles per hour); the graduations shall be of 1, 2, 5 or 10 km/h and also of 1, 2, 5 or 10 mph and the values of the speed indicated on the dial shall be multiples of 20 km/h and multiples of 20 mph. I can assure that the speedometer fitted to your vehicle meets this stipulation.
There will always be areas that are open to constructive comment and feedback such as yours is always greatly appreciated. Consequently, we have retained a copy of your comments on our Customer Care Database for our future reference.
I understand that we may not have met your expectations with your case; however, you may wish to contact Motorcodes who are an independent ombudsman for the Motor Trade. Please find details below.
Society of Motor Manufacturers
71 Great Peter Street
London
SW1P 2BN
http://www.smmt.co.uk