Different animal but my old 1st gen W250 cummins would get 21mpg at 70mph empty and about 14-15mpg towing my fury in a 26' enclosed. It got around 14mpg with less weight in that trailer before I turned the fuel up and got the 16cm2 housing. Speed was always the biggest mpg killer for me. Tug the trailer at 65mph and it did much better than 75. 65mph with the Fury on an open trailer and I would get 19mpg, hardly any drop at all.