I have been looking at Honest John you can look at some real life fuel consumption figures for real owners, not the manufactures inaccurate claimed figures, the BMW X1 2.0 petrol actually comes out very accurate.
I inputted my Ford Kuga 2.0 diesel powershift it came back 38/39 the on board display shows 45/47mpg,,when I fill up it is approximately 40mpg.
I did input my old Honda CRV, Audi A4 Advant and Suzuki Grand Vitra the real life fuel consumption very similar to the figures used to achieved.
Unfortunately I have suffered a brain injury and occasionally say the wrong thing.