Join Date: 11th October 2010
Location: Wallasey, UK
Thanked 516 Times in 402 Posts
I've never driven an auto, so no idea about lower MPG, but the DPF comment is a very good point, the 37mpg could well have been during a regen cycle.
On my motorway trips, I get anywhere between 47-50mpg, sometimes more, so I can't see how you should get a whole lot less. I still think you've probably got some kind of issue, never known a 2.2 diesel to give mpg in the 30s on a motorway :/