Susanbythesea

thanks for the reply , I’ve only had it a few days so will do a manual calculation... if not up to spec is a bmw garage ideal for checking the problem or will my independent but very good garage be able to sort it ?

New owner here.... I have just bought a 2012 low mileage 120d auto convertible , previously had Saab 9-3 auto convertible and prior to that Porsche Boxster .... I changed to a diesel as I cover a lot of mileage now but have found I am only getting about 38-40 mpg on predominantly motorways/ dual carriageways compared to my petrol Saab of 34mpg, list mpg is over 50 ... is m6 mpg normal or is there a problem ?