Last September I replaced my C220CDi Mercedes-Benz Estate (85,000 miles) with a Blue Efficiency C200 CDi Mercedes Estate – both diesel automatics. Over the life of my old car I averaged about 37mpg and on a long run sometimes got up to 50mpg. In my new car (7,000 miles so far) I am averaging 37mpg, and on long runs have never got much above 45mpg. I have not changed driving style or journey pattern. I calculate that the fuel consumption I am achieving in the new car needs to improve by 30 per cent to get up to the quoted figures.

I have looked at the tests and understand that they are supposed to be indicative, and are not real life. The car has undergone extensive testing at Mercedes-Benz of Blackburn who are helpful, but in their tests on long runs it achieved about 44mpg with one run at 49.1 mpg, against 60.1mpg quoted in the Mercedes-Benz catalogue. Is it reasonable for me to expect a significantly better performance than I am getting?