I have recently had the misfortune of using the M1 south of Luton, the long stretch which has the 50mph average speed cameras installed. Fortunately the driving school car has an average speed computer function which I reset as I passed each camera and I had calibrated the system against my sat nav. This allowed me to average exactly 50mph and helped me avoid driving for protracted periods with vehicles either side of me. It only needs one driver to sneeze and his fellow travellers either side could be endangered. There is very little ‘wiggle room’ on those narrowed lanes. No doubt other drivers, relying on their hopelessly optimistic speedometers, thought I was risking points on my license but it is my job to know my car. If I had a criticism of the vehicle it would be that I should have also specified cruise control. However the car was very expensive as a driving school car and I had to draw the line somewhere.