I took the car in for its first service today and no problems at all. However, when I was driving home the trip computer indicated a higher fuel consumption than usual. Travelling to the Dealer I got 46.8mpg all on single carriageways and with a couple of road works that held me up. Returning home I decided to go the long way round to miss the road works, and half of the journey was by dual carriageway and motorway. I never travelled over 60mph and would have expected a reading of at least 55mpg, but I only achieved 45.7. What do you think would have caused this?