Now if somebody would make an RV like that with a I4 Cummins for power. Bed in the tail like a V-berth in the front of a boat. Make the interior 6 1/2' tall in the center and make it 7' wide. What would the frontal area be about for that?
I bet it could get 30 mpg
or maybe better yet this motor
http://cumminshub.com/2.8l-cummins.html