Fuel mileage for all you 6.7 owners
 

What is everyone getting for mileage on your 6.7s? I want either a CR 5.9 or a 6.7, but would still like to stay around that 20+ mpg mark. Do the 6.7s get the same mileage as the 5.9s if the smog regulation stuff is taken off? What are the 6.7s getting with programmers? Any information would help me decide in the decision!

TIA,
Nathan

Everything deleted for me and i get about 17 on the highway. If you want the fuel milage get the 03/04 555 CTD i was seeing on the average around 22mpg, Ive heard others getting better then that.

Both of my trucks are stock right now. My '06 2500 gets around 18 MPG, and my '08 3500 gets 15.5 MPG.

I plan on doing a little bit to each truck to get more performance and mileage, but most of it is just replacing or adding the things these trucks should have came with.


Kris

Here are the averages from my fuel records for the three trucks I've owned. All driven unloaded. All automatics.

2004.5 2500 QC 5.9L (4.10 gears) = 17.3
2007.5 2500 MC 6.7L (3.73 gears) = 16.0
2009 3500 Dually MC 6.7L (3.73 gears) = 15.1

fuel mileage highway averages 17.5 - 19
town 12.5 - 14.5
speed is the biggest variable. The peak fuel economy appears to be 40 to 60-65mph. It deteriorates as you drive 75. Even more so above that. All of my highway mileage is long distance with trips lasting at least 2 hours in mountain driving conditions. I drive the speed limit posted and that seems to provide the best mileage. Colorado interstate is 75mph. The truck is stock with the bluetech exhaust. The only aftermarket change is a larger air intake.

2010 about 17.6 mpg.

mileage
 

getting 17-18 going 65-70 mph 15 going 80-85 mph don't know in town stuff
All stock 2009, 6.7, 2500 bluetec 30K miles on truck

I WISH I had my 5.9 back. The 6.7 (stock) does not even come close to the MPG I got with my 04.5-5.9. The only two good things about the 6.7 is the 6 speed auto and the e-brake.

Totally disappointed in the 6.7 (MPG wise)

After all surgeries on my 6.7 I see on average at 105 KMH or just a bit over 65 mph on the flats...19 and change. Drop that down to 60 mph or just under 100 KMH and I start getting over 21 mpg...not by much but I have managed that many times, hand calculated.
However, if I start running in the 70-75 range it drops like a stone. 16-17 if I am lucky...15 on average.
Towing is different. I match or exceed my 07 5.9 towing all the time...UNTIL I get over 65 MPH. Disciplining myself to keep the speed down took some effort but in the long run it made a noticeable savings and when I was logging 8-10,000 miles a month the savings and the stress reduction where well worth it.
I run a long bed conversion Mega Cab Long bed 3500 dually. Tires all set at 80 psi. I was running my own air intake [old Scotty Air 5] with smooth bore flex hose to the turbo, 5" exhaust, Smarty on SW 3 and pressure at 1. Deleted the dpf and all the smog stuff except for the EGR cooler...its next.

When I look at my monthly expenses and my logs/notes, there was a lot of money wasted when the truck was stock.

Scotty

Thanks for all the information guys. I think if I could average around 19 I'd be OK buying one. What gears in the rear end is everyone running to get their mileage?

373

I think most that get the best mileage are running 3.73 or 3.42... I have the 3.73 and pretty much just tow my toyhauler with it. I've never even ran an tank of gas out without a tow behind at some point! I get about 10 towing. Used to get 9 or less before the right modifications were made.

My '03 305/555 with a KORE suspension and 35" Toyo MT's averaged 18mpg hwy.

My '07 325/610 5.9 with the same suspension and tires got 13mpg.

In my opinion, with mileage it's the luck of the draw. Some trucks just seem to get better mileage.

The thing to get if you was on the road alot would be a nice gear splitter
http://www.gearvendors.com/dmanual.html... talk about saving some green.

I have 3.42 gears in my stock 2009 truck.

Had 3.73 in my 2004.5. Got better MPG.

The emission equipment on the 6.7 really kill it mileage wise. Maybe someday I'll understand how burning more fuel to go the same distance is better for the environment[dummy][dummy][dummy][dummy]