I have owned my 2500 NV HD since March 2012, have 6500 miles, and I get 11.0 mpg towing a 31' Airstream trailer in northern Pa, and Northern Ohio. I get 11.8 mpg avg highway and very little city NOT towing, too. The van is excellent in every way, except the very poor mpg. The averages are over 20 fillups with 87 octane fuel, properly inflated tires, and so on. I have about 400 lbs, (toolbox, dive equipment) in van. It is odd, the engine runs so smooth, & I drive moderately. So I wonder if my van's transmission is in tow haul mode despite the indicator being off. Or is there another solution, like a superchip like diesels use? Also, what about warranty issues?
