Yeah the GM 6.0L gasser was never know as an econo motor. I have 2002 GMC 2500 crew cab, 4WD with the 6.0L. Bought the truck with 70,000 on it and now I have 215,000. The truck came with a K&N cold air intake, , , that is/was the most irritating thing I ever heard. Took it out and threw it away and put the stock air filter and ducting back on. As said previously, I would really question what if any PROVABLE gains are obtained by an after market cold air intake.
Anyway, when I do drive my truck unloaded, the best gas mileage I ever got was just shy of 14 mpg, , I almost fell over! Otherwise it's 13.5 - 13 3/4 MPG until they switch over to the "winter blend" fuels up here in the north land, then it's almost exactly 1 MPG less. And I drive like there's an egg between my foot and the gas pedal.
Towing, the worst fuel mileage I ever got was towing an enclosed deck-over snowmobile trailer, 8' wide X 26' long, 4 sleds, probably approaching 6000 lbs. 5.5 miles per gallon! I have never seen a gas gauge move so fast in my life!! That was one tank, otherwise it was 6.5, maybe 7 mpg.
To the point of drag from a trailer, the next snowmobile trailer I got was an "in-line", 7' wide X 25' long, big V nose. I could easily get 8.5 to 10 mpg pulling that trailer with 4 sleds in it.
Towing and fuel mileage should never be used in the same sentence. Just translate that into how many smiles per mile and you'll be just fine.
