Over the last few weeks I have been very much in Miss Daisy mode with my 320D and managed to get the mpg up to 59.7. Nursing a cracked windscreen can do that to you
The 330D E90 hire car I had as a replacement was great fun to drive until the last week when I was determined not to have to put more fuel in and so Miss Daisy mode for that too. Over the last 150 miles I managed to get it to 48.7 with such timid driving that even Micra's were over taking me
I can only imagine that with a careful right foot in a 330D F30 there would be a better mpg than the E90 but it really takes the fun out of it and what's the point in that???