Back on the road. Just turned 30K miles and expect another 10K in the next two weeks. The haul to Phoenix from Pa. was typical of fuel mileage (hot topic in light of the price) with this truck.


Towing 10K#'s the mileage varied from barely 8 mpg to over 13 mpg. That is mostly at 65 mph so the variable must be related to elevation and head winds. Out West, the elevation and winds drop the mileage dramatically. Midwest and East seem to be the best.


The return runs without a trailer have a third issue....speed. Out West where the speed limit is 75mph, I run around 78 mph and barely keep with traffic. Fuel mileage drops to 17 mpg. Don't know if the elevation issue or wind is a major factor but assume it's the high speeds.


When you hit states with the 70 mph speed limits the mileage goes up to 19 mpg as I drop speed to 72 mph. In states like Indiana, Illinois, Ohio etc. the speeds are 65, the roads are level and the fuel mileage is a solid 21 mpg.


Wish I had a 7 speed transmission, or dual-ratio rear, to drop rpm's at higher speeds. My conclusions are the Cummins needs to be kept below 2,100 rpm to have real good fuel mileage. That may be a greater issue than wind and elevation when not towing.

You are doing pretty good on mileage. I get 19mpg at around 65 and 78 I will drop down to about 15 to 16 mpg. Some are claiming to get 24 mpg at 75.

The two wheel drive my neighbor has DOES get in the mid-20's on a regular basis. They have less profile and less drive train to turn.


Solid 20mpg last week for a thousand mile stretch. Kept the speed right at 69 on my gps. Add just one more mile per hour and it's expensive. I get bored and like to play with things like this, day after day after day after...

Do you know what timing you have yours set at or on those is it computer controlled.


Mine is a 97 and set for about 14.5