My really knackered old 2.5D Transit used to do about 30mpg, despite it's 186k on the clock, but when I bought a nice shiny VW LT28 it nearly killed me in fuel costs. I never got round to working it out as I was too scared to! I sold it after only a few months because it was just costing me too much to run - was nice and fast tho compared to the trannie!
Matt.