If you signature is filled in we will know what your driveing.
How your driveing would be nice to know.
Town, town w/trailer
Mixed hwy town, mixed w/trailer
Hwy, hwy w/trailer
Wind drag is a big factor on the hwy so how fast do you drive?
Also please try to get an AVERAGE (several thousand miles) not just the one time when you were pulling a trailer up 7% grades and got 6mpg.
Or going down hill with a tail wind drafting a semi and got 28mpg.

 

Just got the truck. And made my first long trip from Fairfield Texas to Laffeyett (sp) LA. Approx 400 miles and the over head was reading 18.3 when I parked it, It still has about 3/8s of a tank left. I havnt had a chance to fill it back up and check the accuracy yet. It was all Interstate. I-45 S to I-10 E. Average speed was 70-75.

 

I got 15.5 one tank and a little over 16 on another all hand calculated and thats with EGR unplugged and edge with attitude! mixed driving but it's been cold so summer it should be much better as I wont be using the high idle to warm it up and wont have winterized fuel

 

solid 19mpg empty freeway 65-75mpg smarty jr. tow setting, tq and timing on default. 1200 miles straigt through.

 

I average about 19 highway at interstate speeds (75mph Colorado). If I drop back to about 65 mph I easily average over 20 to 21. In town the truck gets 13.5 to 14.5. Hauling a light slide in camper over the pass at 55mph the truck gets about 16 mpg.

The truck has 26500 miles...mostly highway.

6.7L, auto, 2500, QC, 4x4, Mineral Gray

 

When I first bought the truck I drove it home from st louis to sw pa. I was surprized to be getting 19.5 all the way home on 70 at 75-80mph. For the most part ive been at 16-19 unplugged. 14.5-15 plugged. About 50/50 highway and 2 lanes. I have yet to tow anything but that will be changeing soon.

 

I was getting 12.3 when I first got the truck and when it was broke in it didn't get any better!!! I've had it in the shop 5 times now and they have done everything from reprogram the truck to put a new turbo on it to cleaning out the fuel lines. It does get about 15-16 mpg if I really baby it and drive about 50 mph! It's in the shop as we speak. Even the shop said something is wrong. These trucks are not designed to be babied! I am only getting around 7.5 mpg towing my 8000LB camper. I towed it back the other day and had to run 4th going up a hill floored and still lost speed. This same hill was no problem just 3 weeks prior. The first trip was to the hunting property for deer bow season and the second trip was to the same property for deer rifle season My 1/2 ton Hemi didn't struggle as bad!

 

Thanks for the response everyone.
Next question what was your computer mileage also so we can see how close it is to hand calc.
I haven't bought my truck yet and really trying to get a good idea what to expect.

 

I have 8000 miles on it, hand calc & overhead computer is fairly close.
No mods nothing unplugged avg 16MPG rural country roads 19.5 on the interstates.
Those MPG were hauling empty on occasion I haul a 1 ton trailer but to tell the truth hauling a ton on this machine is like hauling nothing it all very little drop in the milage

Emil

 

06 5.9 37000mil city 16.5 to 17 highway 19 to 20

 

Little over 30k on mine ,hand calulated 490 miles on 31 gallons of fuel in city not bad ,my 5.9 was about the same.

 

My overall average since I got the '03 with just under 25K on it is 19.31

My overhead is somewhere around 4mpg optimistic.

 

I get 13-16 with a dually which tows a horse trailer often. I have never approached 20 even empty with tailgate off. Is there a secret to getting 20mpg?

 

Please fill out your signature so we will know what your driveing.
Why do some get over 20mpg is a good question. I've had 8 so far and none have got 20mpg on average on the hwy.
I did get 21mpg pulling a 30ft goose neck from Denver to KC that was with a 45mph tail wind and I was going 70mph.
I still find it hard to believe that people are getting over 20 in a 4x4 on the hwy without driveing 55-60mph.

Just remember AVERAGE is what I'm looking for.

 

I just did a trip from Boulder, CO to Boise ID, interstate driving the whole way. 830 miles each way. Heading west into heavy winds, I averaged 15mpg (hand calc) going 70-75 MPH. The overhead said 18mpg.

On the return trip, heading east with solid tailwind, I averaged 17mpg (hand calc), same speed 70-75mph. The overhead said 19.5mpg.

EDIT, forgot to mention this is with Edge Juice on setting "1" (economy).

This is all unloaded, stock wheels and tires, and a Carli starter (leveling) kit. Soft top camper shell. It seemed low to me. But, avg elevation was 5000 ft, and probably on winter fuel in CO and WY. So maybe those are factors?

however it still seems low. 17mpg with a tailwind??? Woud have hoped for 22mpg. I wondered if the level kit killed my mpg.

I fantasize about 22mpg unloaded, fwy, at 70mph.