I have a 2015 super duty pick up truck. My average mpg aroun town is 11.
I am not an aggressive driver. We hauled a 37' FITH wheel toy hauler this week end and my mpg was 6. This does not seem correct. Any input???:

 

Mines been 18.9 avg. truck has 49k miles on it.

 

2011 CCSB with EGR DPF DEF deleted (and the exhaust work), TorqTech tuner on level 3 (always). Average a little over 20 if I'm just driving to and from work, about 16-17 around town. I get about 12 when I'm pulling our 33' tag along camper (7600 lb dry weight). Not sure where the problem is, but I would say something aint right. You sure you got a 6.7 and not a 6.2?

 

Seems pretty low to me. I tow a 33'TT and get 11+. This is actual not what the lie-O-meter says. In town I am at 16+ in rush hour traffic and around town. Trip meter B at 10.5k miles reads 15.8mpg,w/ 2500 miles w/TT, subtract 1+mpg that I normally think the computer just adds to make me think its an econo vehicle and its better than I thought I would get when I bought it.

 

Is it fully stock? Maybe oversized tires, for example, that can contribute to miscalculations?

It can certainly very quite a bit based on how you drive, what you're hauling, and what you're towing. My 2011 CC SB 4x4 usually averages about 15, bone stock. It could be a lot better, but I drive it aggressively through the Texas hill country, as compared to driving like an old man through the flat plains of Kansas. Pulling about 17k worth of gooseneck up in the airstream at 85 I averaged about 9.

You should generally be getting better than you are, even with lots of regens.

 

What gears do you have? I averaged 14-17 on every tank depending how much hwy I drove for a given tank. Mine was a 2014 w/3.55 axle.
My friend tows a new 37' Torque toy hauler with his '14. We recently made a trip together. He got 8 towing that big 5th wheel.

 

I have the deeper 3.55 gearing. I always wondered if the 3.31 gearing would've made much of a difference in mileage either way. And if not, why even bother offering more than one gearing choice

 

About 18mpg. Half highway half around town.
11-12mpg towing 18 ft enclosed car trailer

 

I have a 2015, cclb, fx4 with 3;31 gearing. The first 500 or so miles, I got as high as 21 mpg strictly highway. Now, the best i get on long trips is about 18.5. I get around 12 running around town. i can get as much as 13 pulling my 9000 pound trailer if i am easy on the throttle and there isnt a headwind. With all that said, i wish i could tune it to run like it did the first 500 miles. I use the power occasionally and love the diesel pull but i have been spoiled by manual transmission 7.3 motors which broke 20 mpg everytime i drove empty!The regen kills the mileage on these trucks as well...

 

12-13 around time. I can get 18 on the hwy unloaded and 9-11 pulling heavy.

Mine is a DRW with 3.73 gears and a 2013.