Originally Posted by JaySTee
But then I would expect a new 118d to do better than 46mpg - the wifes 1.9d golf will get 55mpg even with some town driving. Although I guess as it was a courtesy car you were driving it "like you stole it" ?
Don't compare to the VW 1.9 TDI engine, not sure what variant you have, but the 1.9 design does turn in some of the most outstanding BSFC figures for any diesel engine. The latest 2.0 TDI Common Rail engine is not as good by comparison.
BMW engines are tuned to deliver a different, more linear torque band, more petrol like. For the average driver, means more fuel is used. The VAG engine is a bit peaky, but if you drive them on the wave of torque, they turn in some very impressive mpg figues. I speak from experience, years with the VAG engines.