i have a 27' enclosed (2 riders, 3 sleds) that i tow with my 2011 superduty diesel. a 200 mile roundtrip with a 3800 ft elevation change gets me 11.8 mpg. i also pulled it recently with my 2011 f-150 with 5.0 gas engine, surprised to get 11.0 mpg, same trip, same weight....my son pulled it today, 2011 eco boost, same trip, same weight, same speed, got 9.0 mpg...a power test between the two gassers on the same hill, both topped the hill at 80 mph, both floored, both in 3rd gear (as selected by the auto trans), his eco out accellerates the 5.0, but after that the trucks are very comparable...but i get consistently better mileage, .5 to 1.5 empty, hiway...about 2-3 better around town, 2.0 better with the trailer...nearly identical f-150s...both great trucks with no problems