MotorTrend Tests the 1500's

no lengthy interstate travel & i always set the cruise @ 5mph over. the only pure interstate stats i can remember was a trip from atl to sweetwater, tn, a little over 200m @70-75 and came up just short of 28mpg. the heaviest i've hauled was a 16' vee nose cargo trailer gross 4000# for 400 miles interstate @ 65-70mph netting 15.6mpg. for comparison, my former 2013 sierra did about 12mpg wirh the same load & same trip. my sons 2014 ecoboost made the same trip with the same trailer with only 2500# @ 60-65 & also netted about 12mpg. i think he's pretty happy with that since his 08 tundra only did 9mpg. her's some trailers i've been looking at. some would probably do better with a 392 gearset.
http://www.trailerlife.com/rv-trailer-news/half-ton-fun/