[Grovsnus]

Originally Posted by BigDave

Do they not have diesels in the states yet? I have the X drive 18d 140 bhp 320nm torque. Fuel consumption does improve with mileage. I have now done 13k miles.

Sadly, diesel in the US isn't the same as diesel in Europe. Over here, the diesel fuel is a badly refined high sulfur product meant for tractors, sold at a higher price than petrol. It would ruin the engine of most modern European TDI cars.

Many manufacturers have (token) diesel models, but they are special US models made to run on the inferior fuel, and aren't very popular. Mostly because the US consumer doesn't know how different modern diesel engines are from the soot spewing engines of yore, yet not politically concerned enough to demand low emission diesel fuels.
And, of course, the powerful corn (maize) lobby in the US fights it, because they want a switch to E85, not diesel.

Originally Posted by BigDave

I do mostly short journeys and average 37-40 mpg in summer. In winter it goes down to 34 mpg. On a long run I average 50 mpg.

Keep in mind that the imperial gallon is rather larger than the US gallon.
37-40 mpg (UK) =~ 31-33 mpg (US)
50 mpg (UK) =~ 41 mpg (US)