2013-2014 6.6L Duramax Fuel Economy

[dicky1243]

Originally Posted by WFD

The only true way to know is by good ole math calculation. Too many report what they see on their DIC...do the math then report. Too many DIC's give an average as well as an instant reading. I think some people report their instant reading while coasting downhill!

I have an 06 GMC and at 55 on the hwy I get 24 mt and I have gotten as much as 17 with out trl. out in Az

[bplantcjf]

I have a 2013 Duramax and get 18-21 without my 5th wheel and 13 with the 5th wheel.

[plocklin]

Thanks wzpsjm

My original thinking was when they combined the SCR and DPF to one unit it may of effected the fuel economy.
Now I am realizing there must be a problem with mine.

[PSU Turf]

I get 23 mpg at 65 mph on flat ground with no load. I get 16 mpg city driving and 11.5 mpg pulling 5000 lb TT at highway speeds.

[keeprr]

I have a 15 GMC 2500 All Terrain 4X4 with Duramax. This summer towed 5er, 32 ft. 10,000 lbs, from Oklahoma City to Virginia Beach and back to OKC. Approx 3100 towing miles, average 13.1 for the round trip at 65 MPH. Two weeks ago, ran without 5er from OKC to Lake Havasu City, AZ, approx 2300 miles and averaged 18.4 at 78 MPH average.

[mike.t]

Thanks Phenom. Great to here someone talking the truth. My 15'Ram 2500 gets 21.5 open road no load. 12 towing 8k trailer and about 15 town.

[hdmtnrider]

plocklin, Maybe it's time for a "Tune-up" (Like some new plugs and all!) LOL. No really, I have a '15 Duramax and I get 14-16 around home in the mountains of N. GA., as much as 19.9 on the interstate (75-79 mph) between Ga. and Ark. I only get 10-11 towing my TH which I would say is around 7,000#. I too would like to find all those roads everyone is getting 20-22 mpg empty and 12-13 towing those big 5er's. Hope mine will get better with mileage as some say. Only have 9,800 now.
Good luck and happy RVing!

[GeeDubb]

I've seen anywhere from 9.5 towing up to the mountains to 24 mpg coming back down empty on the EVIC which is usually off by 2 mpg on the upper end but pretty close when towing....

[DouglasReid]

Originally Posted by plocklin

I hear people claiming a factory 18 to 20 mpg (with no load) with the 6.6L Duramax trucks.

I get 13.5mpg unloaded on the highway with my 2014 Silverado 2500HD running the 6.6 Duramax Diesel. I have a hunch that the older models get better fuel economy than the newer ones so I am reaching out to ask anyone that has a 2013 or 2014 6.6 LML Duramax to ask what is your fuel economy.

I am trying to find out if it is possible to get the 18 to 20 MPG like I know others are getting. I know this type of discussion opens a can of worms with people suggesting modifications but I am interested in why some people get great fuel economy with a stock setup and some do not.

Thanks for your input.

I have an 08 Silverado 2500HD with 36000 miles now. It is totally and completely stock, NO Mods whatsoever. On the highway, unloaded I get about 18.9 IF I keep the speed at the posted limit (65).

If I speed up to just under 74 (which keeps me from getting stopped for speeding) I get 16.

The 08 has the LMM engine with a DPF and EGR. Yours is an LML that as well as a DEF system. Im not sure how the addition of the DEF affects your mileage.

If I were you Id go to the Duramax forum and look through their older posts. I belong and the wealth of knowledge on that forum regarding these engines is astounding!

[Photo Lab]

In real life...not in manufacturer certifications, tire size and axle ratio can make a HUGE difference, as well as the weight of the driver"s right foot. My old TV was an F-250 crew cab long box with the 6.0 diesel bone stock and with 3.73 axle. Around town driving generally gave me around 19, towing our 29' fifth wheel mileage was more like 10 to 11. Generally at the limit, and using cruise.

[ronp]

I have the 2014 Chevy Duramax, pulling a 2017 Cedar Creek 33ik fifth wheel. I get a consistent 10.8 to 10.9 pulling the fifth wheel. Without the fifth wheel, I get 19.6 to 19.8 , out on the highway. I'm very happy with that.

[mike.t]

The majority of all these replies are very honest. It's refreshing not to have to read about 15.5/16 towing \25 26 highway.
Thanks

[nwminnesota]

Have 2014 dmax with 30k on it city/freeway 17.5 to 18.5. Freeway driving from Bismark ND to Twin Cities MN winter grade fuel and I got 21 mpg. Towing at 74mph with 5000lb trailer I got 12.5mpg and at 64 mph with same trailer I got 14.5 mpg. I have checked the dic with hand clacs and come really close of each other. My understanding the DIC is more accurate because the computer knows how much fuel goes in or knows pretty close what is used. JMO... 15 mpg seems pretty low. Maybe you had a regen when you calculated that tank.

[usraptor]

2011 Chevy 3500 Quad Cab LB 4X4. On level highway at 65 MPH I log a consistent 22 MPG on the DIC. Every increase of 5 MPH results in a decrease of approx 2 MPG. At 83 MPH (speed limit in Utah is 80 on most highways) I get between 17.5 and 18 MPG depending on the grades. Mixed city and highway driving (non-towing) is anywhere from 13.5 to 15.5 MPG. Towing our 2012 Sanibel 40 foot 5th wheel at 70 MPG it ranges between 9 and 10 MPG, again depending on the grapes. In 2014 we towed the trailer all the way to New York and back to Utah and averaged 9.5MPG. BTW when I check the DIC for gallons used vs how much gas I put in the tank it's always within .5 Gallons. Just saying.

[plocklin]

labarn,

I believe you are correct. I have not seen any other option then the 3.73 on the Duramax.

plocklin

[Wileykid]

Have a '16 2500HD 4x4. Pulled a 9K pound toy hauler 7K miles this summer from California to Virginia and back. Average was 11.5 mpg for the whole trip. Saw anywhere from 6 mpg (dang winds) to 14 mpg towing. Average 21 hwy/16 city not towing. Buddy has a 2008 2500 with 330K miles on it and is getting about the same.

Mark

[djeirlessr]

I recently bought a '16 Silverado 2500HD Duramax Diesel engine. I know nothing about Diesel engines except I like it better than my gasser. The best I got out of my previous Tundra was 17.5 without towing our fifth wheel at 65 with cruise on. I did not buy my new truck for the fuel mileage but it is better that the Tundra on the highway. I have a little over 4,000 miles on the new truck and still trying to figure out the fuel mileage. I was told that the truck won't be broken in until I get 20,000 or 30,000 miles on it to be consistent.

Short trips it seems I get anywhere from 11 to 17 MPG without towing our trailer. But on the highway setting cruise at 75 for about 50 miles I got 20.4 MPG. Setting cruise at 70 for the same distance I got 20.7. I took a roughly 120 mile trip set cruise to 65 and got 23.1 MPG until I got on a road with red lights. I was not towing anything and I reset the average MPG every time I got fuel or started a trip. The crazy thing is that my display shows the best of 30.7 MPG I don't know what long hill I came down to get that.

My main reason to buy the new truck was because my DW and I plan to do a lot of traveling next year and I was not sure my Tundra could handle it. Also, the $12,000+ discount on the truck. My trailer is roughly 10,000#. Took it to Florida (North Fort Myers) the beginning of this year. I drove 1,003.8 miles and got 11.061 MPG with the Tundra. I did the math to get the MPG. I have not had a chance to pull my trailer with it. The camper is at dealer for some minor repairs. Only taken 3 and a half months so far might be done this Friday. I'm not holding my breath but definitely need it the last week in December. We are heading to Florida again.

[SidecarFlip]

Not on the subject of owning a diesel pickup but on the subject of RV dealerships and their absurdly long repair intervals... that seems to run through almost every thread on this site...

If your vehicle dealership operated that way, they'd soon be out of business.

I find it amazing how long people wait for repairs, warranty or otherwise. Just absurd in my opinion.

Something basically wrong with that business model in my view.

[doc73]

2015 4x4 crew cab. Get 20 on highway, 17 to 18 typical mixed driving. 12 to 14 towing.

[plocklin]

Originally Posted by hdmtnrider

plocklin, Maybe it's time for a "Tune-up" (Like some new plugs and all!) LOL. No really, I have a '15 Duramax and I get 14-16 around home in the mountains of N. GA., as much as 19.9 on the interstate (75-79 mph) between Ga. and Ark. I only get 10-11 towing my TH which I would say is around 7,000#. I too would like to find all those roads everyone is getting 20-22 mpg empty and 12-13 towing those big 5er's. Hope mine will get better with mileage as some say. Only have 9,800 now.
Good luck and happy RVing!

I’m checking mine over but as far as a “tune up”, what can you do on a diesel other than change the oil and air filter?

I just refueled after 484 miles and 32.5 gallons of diesel. That’s 14.88 mpg with mostly highway miles.

I did check my air filter and was shocked at how dirty it was. I vacuumed about a cup of dust out of the air box before I put the new filter in. The transmission was about a pint low so I topped it off. So much for the “multi point inspection” from the dealer I bought it from.

It does run much better now and the shift points seem to be better driving around town. Before it would rev to about 2400 rpm before shifting where now it shifts around 1800-1900rpm. This is with minimal foot on the accelerator. I will see if my fuel economy is gets any better next time I buy fuel.