Just got back from Tampa, back home in nj did a little over 2000 miles. Averaged 18 a gal.:B Oh forgot to mention its a desiel. I know my profile says maverick truck camper that was two rvs ago I can...
I would guess the OP has a Sprinter based "C"... that or a Trend with the diesel engine. Either way, 18 MPG is par for the course. I'd expect that with a Winnebago View, FR Solera, or any other "C" on that chassis.