Gm 6.0 litre v v t v8 tow vehicle engine

[SGSST109E]

I bought a new 2500 2014 crew cab 6.0 with 4:10 gears to replace my 1999 suburban with a 454 that was getting tired. I tow a 28 foot trailer total weight about 9,000. I actually get better mileage in tow mode. Towing I get 8 to 11 mpg depending on terrain. When not towing I get 13.5 as an average. Straight highway by itself I have hit 15.4mpg.