Just made a 1,832 mile trip to Pennsylvania from St Louis and back. Mostly interstate driving and cruise set on 75-76 on the way there with no trailer and averaged (according to the dash mpg) 18.1. 3.5 Eco with 3.31 gears. I went there to pickup a trailer. The trailer is an all aluminum flatbed that has a vinyl cover on a steel frame mounted to the deck. The trailer weighs 1,800 lbs. Traveled the exact same route back and did have a headwind for the first 350 miles of the trip home, but lot's of traffic around Columbus and Dayton, OH but got close to 14.2mpg, mainly due to the fact we were going less than 50 mph much of the time. Once we cleared traffic we reset the mileage and mpg and was able to resume Interstate speed, we set the cruise at 73, but fuel mileage steadily dropped. The rest of the trip, we averaged only 12mpg. I have to say I am more than disappointed with the mileage with an empty all aluminum trailer. The cover on the trailer has a wedge shape to it so it is at bed level at the front of the trailer rising to a high point of 91" in the middle. I did find that if we lowered the speed to 62 - 65, we could get 14 - 15. So, moral of the story - if you want fuel mileage while towing, don't push this engine much above 60mpy

 

I went from 19mpg to 12mpg with a trailer in a diesel...You're not going to get great mileage with a trailer period. Looka at it this way most trucks don't get 14mpg unloaded/without a trailer period.

 

I get 18.6 mpg with mixed driving and 23 mpg all highway. Still breaking her in :-)

 

My 13 with the same engine/gears gets 17 mixed. If I keep my foot out of it on the highway I'm getting about 20mpg.

Last weekend, I towed 2 ATVs 300 miles round trip on hill roads. On the way out, with a strong headwind the average was about 13mpg while driving 65-70 most of the way. Coming back, I used tow/haul and averaged around 15mpg with the same speeds. Winds had something to do with it, but it also didn't seem to downshift as quickly on hills. Far better than the 10 year old hemi it replaced.

 

This combo is great for me, got over 28 mpg on a short highway trip, just me in the truck, no cargo and not towing. MPG dropped when I ran into stop and go traffic.

 

I tow a 25' camper with mine to Florida every year. I average between 9 and 10 mpg towing, I average 16 everyday driving. Towing through the mountains in TN pose no problem at all. I'm happy with mine.