I have a 1994 K2500 extra cab pickup, 4.11 gears, auto trans, 265/75/16 tires, HX35w turbo, 4" diamond Eye exhaust, stock tune (I know a tune specific to the turbo would help some, but no funds for that yet). With the tire size and gearing I get 11 to 13 mpg on winter diesel, and 13 to 14 on...