Towards the end of last year I averaged 54mpg on A & B Roads in the car I use for work and I was on a round trip of 130 miles daily and believe me my foot was to the floor wherever I deemed it safe to do so around the Brecon Beacons and Market Towns such as Hay-on-Wye, Leominster and the retrospective villages associated with them. The car is a 55 plate Mercedes CLK270 Cdi and moves so the figure shown on your picture not not surprise me.