I've seen as high as 22. 9 mpg by hand, O. H. was 20. 9. This was 531. 9 miles and 23. 16gal.
Just drove to NM with my 7x18 enclosed trailer running 70-75mph on the way back got 14. 7mpg by hand, O. H. was 13. 7.
My mileage has steadily improved. Broke it in hard and not had any problems...