Travelled to and from The Greenbrier in White Sulphur Springs W. VA from Norfolk- just under five hours each way- a lot of mountain grades - avg 75+ mph- with 4. 10 gears got avg of just under 15mpg- unloaded with OD off for stretches of steep grades- near 3 grand rpm- I really liked the power and it may be my imagination but the BHAF seems to have given it a kick in the pants- have 7800 miles on it and mileage seems to be increasing slightly- the low gear really does make a difference in the steep stuff- saw an interesting set-up on a 3500 CTD Dually going the other way- a car carrier mounted on the bed diagonally- he had two small sedans and a Ford Escape on the thing and was bringing it up those grades!!!!