My speedo is running at exactly 10 miles an hour faster than I am driving. (ie I am doing 30 it says 40) I am taking a driving test in it in a couple of weeks and need to rectify the problem as quickly and cheaply as possible. The auto electrician was meant to have recalibrated it before I bought it, as, on my test drive, it hit 60 before I had even left the forecourt (well according to the speedo at the time!). It was certainly better when I got it but when going through speed indicators?or using a sat nav, it clearly shows this 10 mph error. Any suggestions gratefully received.