That argument is mute because I have a bighorn without the etorque and a 3.21 and I’m getting 13.77 mpg on the interstate it’s horrendous.Break in mileage? Perhaps get a bed cover? You don’t have a signature with your truck but is it a loaded crew cab with more weight? But my main observation is there is no way the rated MPG was for 3.92 gears. That is an option and I would expect it to significantly affect highway mileage. Maybe not and would be interesting to see what others are getting with that rear.