mine was hand calculated.

and it's pretty tough to keep me from feeling good whenever I drive that rocket ship.

 

2013 Megacab dually 4x4 with 4.10 gears and the 68R tranny

14.8 mpg on a 1200 mile road trip doing the speed limit with 4 people and a couple hundred pounds of luggage in the bed plus another couple hundred pounds of diesel in the aux tank when it's full. DEF usage was minimal but I don't remember the quantity. I think this mileage is horrible.

On a separate 2000 mile road trip pulling a 41-foot 5th-wheel I averaged about 7mpg and used LOTS of DEF. About 1/3 of the trip was tailwind and the rest strong headwinds.

 

That is about exactly what I get with my 2008 (3.73 gears), was hoping to gain a little with the 2015.

 

Sorry, it took so long to reply. I have the Aisin with 3.42 gears.

 

My 14 with 5200 miles I've used 5 gals of def. I figured that because most of my driving is in town or rural roads that's why I use a lot. My mileage average is 17.5 hand figured and 20 electronic . 342 gears. My 04 with 411s and a mileage module got 21 hand figured. Oh well I love my truck and it gets what it gets . I keep a log with every fill up and miles plus were I got my fuel. One place had bad fuel and I was lucky to get 15 mpg on a 200 mile trip with just me in it . was never so glad to need fuel again! Lol sorry this was so long.

 

Picked up my 14 on March 24, 14 and headed to TX on March 30 with 850 miles on truck and 5er in tow. Over 4,000 miles on truck when I returned home to PA.
Started out at 7mpg towing and was getting 10.3 by the end of the trip. Used over 15 gal. of DEF on the trip.
I was told by an old diesel mechanic, who I was complaining to about the low fuel mileage on my 04.5 Ram when it was new, as your mileage goes up your mpg will get better and it will top out at around 150,000 miles. He was correct, my 04.5 was getting 20+ mpg at 150,000 miles.

I have already gotten 20+ mpg on my 14 on a non towing trip. As the towing mpg goes up our DEF usage should go down as the 2 are related.

I have about 5000 miles on this tank of DEF, with 200 miles of towing, and the EVIC is saying I need to add DEF. 5000 miles is the number I have been hearing as the average for a tank of DEF for non towing.

 

That's exactly what I have experienced. 2.5 gal DEF for about 500 miles heavy towing.
9.3 MPG as well.

 

You have to calculate mileage. If you put 30 gallons in and get 600 miles on the tank you get 20mpg.;-) Towing a U-Haul car trailer with my srw regular cab diesel 2500 ~8500 pounds I got 13.8mpg on a 3500 mile trip. Regular driving, I get 17.5mpg to 20.5mpg depending on the fuel and foot. Best on a tank is 33 gallons in 727miles down the road with a good tail wind (22mpg), 45,000 miles on truck.

 

Just finished the first trip with the truck. 3250 miles total, WI to FL and back. Pulling a 38' Jayco Designer 5th wheel, sorry I don't know the weight of it, but its big with a 13,500 GVWR. Basically ran around 5 mph above the speed limit all the time, so in the 75 mph range a lot of the time, yes even up the mountains

Averaged 9.03 mpg for the trip, the computer was always high by .20-.30 every time.

As for the DEF well went through around 9 gallons of that junk, so that is about a gallon for every 360 miles.

Used way more of that stuff then I thought, oh and trying to find the 2.5 gallon jugs on the road is not an easy task. Multiple gas stations and truck stops all only had 1 gallon jugs, ended up having to go to an auto parts place to find them. Also when the DEF light comes on and the gauge is on 0 the tank won't quite take 5 gallon the last quart or so runs down the side of the truck.

One thing I haven't seen is people talk about effective mileage when you figure in the price of the DEF. So not to bore you with all the math.

My 9.03 drops down to 8.66 if you figure in the DEF.

This is still I would say about 1mpg better then my 2008 got, but not as much as I was hoping for. But the truck pulls much better at speed then the 08 and downshift holding speeds on hill amazingly.

 

Interesting discussion guys. I am actually on here to see what the new Cummins powered trucks are getting in regards to fuel mileage. I went from an 06 Dodge to a 2011 Ford to a 2015 Ford. I loved the 2006 Dodge and the 2011 Ford. The 2006 got pretty decent fuel mile and the 2011 Ford got excellent fuel mileage. The 2015 Ford mileage is not near as good though and thus it has me looking to see if I should consider going back to a Cummins.

 

Just did another fuel check the other day. This was mostly freeway driving.

Actual hand calced mileage was 16.05, that wonderful LIE-O-METER said 17.7

And that my friends is where all these outrages mileage claims come from, might as well turn that thing off and not have it.

 

Almost 15 mpg in a 4.10 geared dually if the speed limit is 75-80mph aint bad. I wouldn't have expected much more than that. Now if the speedlimit is 65 then I'd expect more.