I think with my '94 Dodge pulling the trailer pictured but slower on dirt roads I got around 14 mpg? Not towing, almost 20 mpg, if I remember right.
With the 06' we got 17-20 mpg! (I loved that truck) With out a trailer I could get 25+ mpg with the way I drive.
With the '10 I average 11-13mpg towing with the Wilson loaded. Empty or not towing 15-17 mpg. It seems to do better when you get on the freeway and let her stretch her legs.