Chevy Duramax Fuel mileage

[rrbowman]

I am looking for an honest answer from actual campers. I am considering buying a used 2005-2008 Chevy 2500 w/Duramax with a Alison Tranny to tow a 10,000 - 11,000 Fifth Wheel. Those of you that have a combo similar, what kind of mileage do you get when towing and not towing? I know that is subjective because of driving styles but I consider myself a driver trying to get the best mileage. I have been told 22mpg around town and 16-18 when towing, is that possible?

[perk76]

I have a 2003 Duramx 2500HD with Allison transmission, crew cab, long box. If I drive perfect non towing expressway driving I can hit 21 mpg. I just towed a 750 mile trip through mountains from Michigan to Virginia. We got 11.5 mpg and that was driving with cruise control most of time at 65 mph. I tested a small flat sample size and best I could get was 13 mpg.

My fifth wheel is a 29' Laredo rl.

[RnTBnB]

My TV is a 2007 Chevy 2500HD Classic with the Duramax/Allison, and my trailer is in that weight range. Without the 5er I get around 15 highway, and with it I get around 8-10, depending on hills, etc. I tow at about 60mph.

[tvfrfireman]

Devocamper wrote:
We have a 3500 dual DRW,4 wheel drive,duramax/allison so it is heiver than the 2500hd I get 9-10 towing with the trailer around 14K . I dont think your going to get much more than 10 towing. I get 14 avg combined city /highway driving

I too have the dually and approximately the same mileage. If fifteen MPG was what it got towing, all the other manufactures of trucks would be out of business.

[rrbowman]

Thanks everyone for your input, That will help me with my decision on a heavier truck. I am presently pulling my fiver with a 2005 chevy 5.3 v-8 1/2 ton pick-up and need to upgrade soon.

[SandSOrrell]

You probably have enough answers to let you get an idea of what to expect. Here's some more data. I have a Chevy 3500 DRW 4X4 D/A and pull a fiver weighing in around 13,500 to 14,000 or so fully loaded. Towing I get between 9.5 and 12 mpg, depending on winds, mountains, or flat. Unhitched on highway I get about 16-17. In town less maybe around 14-15.

[AZ_T_T]

Thanks for the info pressure_welder. I guess I should be happy I don't have to deal with the Canadian cold!

[pressure_welder]

AZ T&T wrote:

pressure_welder wrote:
I have a 2012 denali dually dmax/allison. Love it to death, before i did the full H&S delete w/ 4" dual exhaust i would average 15-17MPG max due to the regens, and about 9-10MPG towing. Did the full delete and no word of a lie got a hand calculated 24.6MPG highway on a night drive with zero wind with the cruise set at 100km/h so that was a picture perfect "ideal situation" but in a real world day to day i get about 18-20.

Are you worried about the full delete affecting your warranty? I would love to use a programmer but I would hate to do anything to void the 100k power train warranty. Also in AZ we have emissions testing and I wonder if it would have a negative impact on that?

Fortunately i am in Canada and we dont have emissions testing thus far so were good in that regard. As far as warrenty goes its kind of a long story but basically my father inlaw is in heavy construction and between him and myself we have 5 denali LML duramax's in the family, everything was good with them until the winter and boom! MAJOR DEF fluid issues to the point of where he had to ship a few trucks out for repairs multiple times which as you can imagine is BIG bucks for someone in business, SO he literally had 5 custom built Cummins engines to drop in the GMC's just about ordered until i told him about H&S, and it wasnt 2 weeks later and all of our trucks were deleted and running one million times better. Our dealer who is the dealer principal worked with us and is still honouring our warrenty due to our excessive issues with the DEF fluid in the winter and other affiliated DEF problems. Mostly because he knows our driving style and we drive respectably and arent in it for the HP gains, also i would imagine the fact that my father inlaw in the past 5-10 years has bought well over half a mil in trucks from him. The dealer knows we just simply wanted to delete the emissions crap. And running the tow tune "50HP extra" wont hurt the truck in any way provided your not trying to race everyone you see.

[pinesman]

'07 classic D/A DRW 4wd stock. I get 18-19 with the tonneau folded down empty. Flat land towing my fiver usually 10-10.5. If it is in the mountains, subtract 1-2.

[Cajun_Bill]

"The single best "mod" I have found is keeping my louvered tailgat on all the time, I actually calculated a .5 MPG improvement."

I don't have a louvered tailgate, but have been thinking of getting one just to avoid having to lower the tailgate when hitching and unhitching. I know it's just a tv show, but Mythbusters did a segment on that and their research claimed it didn't help mileage, but I've seen the way the wind whirls when I've got something dusty in my bed and it would seem to me that it's got to help to have the louvers.

[BobsYourUncle]

2007 D/A dually 4WD:
I always have a load on my truck with a rack and toolboxes that weigh about 2000 pounds.

Running like that I get about 12MPG (based on Imperial gallon)

With my 27' TT in tow it drops to about 10 - 11. This is actual, as calculated by mileage and what I put in the tank. The DIC is not an accurate representation of what you can get.

The absolute best I have ever got is 17 empty, when the truck was new, before I put my rack on. And driving like there was an egg under the throttle pedal.

[aruba5er]

2011 D/A around 10,700# 12.2mpg last time out. 17/18 mpg as a daily driver.

[JoeWebPage]

2004 D/A with tuner. I get around 20mpg empty on highway, sometimes up to 23. City is about 15 - 17. Run about 75 on highway.

Towing 12.5K 5er get 10 to 13 running at about 62. Drive in Colorado mountains a lot so mpg affected by that. All those are hand figured. DIC will be higher if you're always heavy on the go pedal.

[Alley_Fox]

If you are planning on buying an older DA, choose the 2006 and newer, everything from 2006 on has the stronger Allison 6 speed as opposed to 5 speed and has the better LBZ/LMM/LXX motor. I am getting ~17-19 MPG unloaded, mostly hwy driving and 11-12.5 MPG calculated towing on moderatly level terrain. I don't calc fuel mileage any more, my DIC is almost exactly 10% higher than calculated so I just accept that reading minus 10%. There are many "mods" you can perform- bigger exhaust, high flow air boxes, chips, etc, but none of these will probably ever pay for their cost but sound and performance are better. The single best "mod" I have found is keeping my louvered tailgat on all the time, I actually calculated a .5 MPG improvement. It's also interesting that I am getting better MPG towing our new heavier 5th wheel, I think the cap makes it more aerodynamic. Just my $0.02USD....

[mwool]

I had a 2009 and now have a 2011. My MPG agrees with others except for - in areas like DFW when they are adding additives to the Diesel I get 2 MPG less than areas that do not add these additives.

If driving rush hor traffic every day I can be to 4 MPG less than normal. Just driving around with normal traffic and a lot of stop lights I am up to 2 MPG less than normal.

[AZ_T_T]

pressure_welder wrote:
I have a 2012 denali dually dmax/allison. Love it to death, before i did the full H&S delete w/ 4" dual exhaust i would average 15-17MPG max due to the regens, and about 9-10MPG towing. Did the full delete and no word of a lie got a hand calculated 24.6MPG highway on a night drive with zero wind with the cruise set at 100km/h so that was a picture perfect "ideal situation" but in a real world day to day i get about 18-20.

Are you worried about the full delete affecting your warranty? I would love to use a programmer but I would hate to do anything to void the 100k power train warranty. Also in AZ we have emissions testing and I wonder if it would have a negative impact on that?