merc 311 cdi van.... MPG?

[JeffC]

I used to run an old shape 2005 311cdi lwb van for 8 months as a race van for the kids karting and it was great on fuel im guessing it was doing early 30s to the gallon, changed it to a 56plate new shape 311cdi 6 speed straight away noticed it was slower and also mpg is nothing like ? dropped to 22mpg, Ive had it remapped which helped with the power but not the mpg, still 22 unless I sit at 60mpg then it will see 27.

anyone else had this, what did they change to make the mpg suffer ? gearing in 6th is pretty much the same as the old van in 5th?