A word of caution about the fuel savings described with the Sprinter diesel - you'll spend what you save in fuel on repairs, assuming you can even get a competent diesel shop to work on them. Regarding other bloated claims on fuel mileage, as some have stated previously, base your projections on the lower numbers. I anticipated 14-15 MPG when I purchased my 2008 Outlook 31C on a Chevy chassis based upon these forums. Have never come close to those numbers, best I have achieved was 8.5 MPG.  Length of motorhome (i.e. weight), cab over configuration (aerodynamic or a brick), speed driven are all variables to MPG.