just finished a 2588 mile trip pulling about 12000 lbs. (5th wheel)DW kept track and here is the low 9.4 and high 11.9-2013 Dodge 3500 4x4 with 6 speed stick-truck did a very good job-I was impressed!...
2001 f350 7.3l 4.11 w/ 40' Cyclone at about 15500 pounds. I get about 9.5 mpg around 58 mph on rolling hills in the Northwest. In the steep mountain areas I get about 8 mpg.
However, when I average overall fuel consumption with commuting on my motorcycle I can claim that between the truck and motorcycle I get over 20 mpg!