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 ?

Hi Sue....welcome to the Club

You certainly like your convertibles then?

That does sound a bit of a low economy figure, have you tried calculating the fuel consumption e.g. fill up with a full tank, reset the odometer, drive some miles and refill with fuel, measure the quantity in gallons taken to refill and how many miles driven, divide the two and then you have an accurate reading. It may be the readings from the MPG display are wildly out.

Alternatively, you may have issues with the engine/fuel system so worth getting checked out as it should give better MPG than what you are getting.

Let us know how you get on with the actual calculations

Cheers,  Trevor

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 ?

I suppose if the car has had service history to date by BMW then it may be worth continuing with it (doesn't work out too expensive for servicing) but any subsequent repairs I would take it to a reputable independent repairer (preferably a Bosch service centre or similar).