20 Duramax MPG.......how are we doing?

[Peekaboo Bruizer]

20 D max AT4 almost 3000mi averaging an easy 15 mpg,  best around 23 on the computer.

Way better then my 19 D max. 
Yeah 10 speed helps but I think there’s more going on then that from 19 to 20. 
Don’t do much towing hardly any just haul in’ my ass around. 
Amazing  daily driver Once you get used to the size. 
tons of cameras & mirrors can pretty much park anywhere if you take your time 

amazing ride big improvement 19 to 20 IMO

[redwngr]

How they are driven/used is everything.

 

I get significantly better than that with my '18 --- with my 'normal' usage.  Which means it doesn't do a lot of miles of short / in town runs. 

It rarely tows.

 

Wish I had a '20 to run for a while to see how it would perform for my application.

Edited November 22, 2019 by redwngr

[powerhaulic]

I am getting 1-2 less with my '20 than my '18 got, same conditions.

BUT i had the Banks Derringer on the '18, not yet available for the '20.

 

[powerhaulic]

I am getting 1-2 less with my '20 than my '18 got, same conditions.

BUT i had the Banks Derringer on the '18, not yet available for the '20.

 

[STGS]

I also get about 2 less than my 17.  Use my 20 exactly the same as the 17.  About a 50/50 mix between towing and unloaded.

[twofish]

2020 AT4 2500, getting 21.0 MPG on the freeway running 75-76 MPH. Truck only has 1400 miles on it, so might get better? This is my first Diesel powered truck, and first GM. Love the truck so far, the power and the MPG exceed my expectations. 

 

 

[CNY_AT4]

I just rolled 1000 miles (95% freeway) and am averaging around 20 with decent hilly roads at 75-80 mph.

 

At times I was in a city or work zone at 60 it was showing around 26.

[deluter]

Picked it up about a month ago and I have been averaging 18 or so ... 90% highway. Sitting on 5,100 miles right now and the best I have seen is 21... Ya I know, 5k miles in a single month... job site commute is about 90 minutes each way

[MoCOgmc]

I've got 1600 miles on mine. I'm getting real world about 16.5mpg with the computer telling me 18. I've got a 3500 Long Bed SRW and live in CO at around 7k elevation. Drive about 50/50 city/highway. 

 

I started using Standyne at about 1000 miles and did notice about a 1mpg increase. 

Edited December 6, 2019 by MoCOgmc

[Colossus]

I am happy to see the favorable reviews thus far on the power train and fuel economy.  The real test will be when they start hitting 30,000+ miles and to see what kind if any DPF and DEF issues pop up.  The LML was plagued with them, while surprisingly the LMM (which only had the DPF) rarely saw any DPF issues.  If things prove to be good on these 2020s I might just see myself getting a Sierra someday when I get tired of my 08. 

[Basketcase]

I as well am getting worse mileage in my 20 than my 17 duramax. Roughly 16/17mpg on my '20, and I would get 19/20 on my '17 on average. My best in MPG in the 30 mile setting was 27mpg in my '17 on a annual trip I do and I did the exact same route this year in the '20 and it was 23mpg as the best in the 30mile setting.

 

Not going to lie, I was kind of disappointed. Thinking the new 10 speed would make it even better on gas... That being said, these diesels always run more efficient in warm weather, and I only got the truck in October and being in Canada it is cold. So maybe it will be better come summer. 

 

I just did our annual snowmobile trip in February. Flat highway for the majority of it and a 7hr drive. My truck had two guys in the cab and two sleds on the sled deck. I averaged roughly 13mpg for this trip which was about 375 miles to a tank (and HALF A TANK OF DEF which has been super good up until this trip). Last year I did the same trip in my '17 but with 4 guys in the cab, two sleds on the deck and a two place wide trailer with two sleds in it. Averaged roughly 16mpg and easily had 425 miles to a tank or more WITH TWICE THE LOAD.

 

I'm thinking it must be the tire size on these new trucks. My '17 had 33s on it (actually like 32.6" or something) and my '20 has 35s on it now (measure 34.8 or something)

[unit]

I have just under 600 miles on mine, purchased March 2nd., and haven't towed yet.  I'm averaging 17+ mpg in local driving and that's almost two mpg better than my 08.  I think that's pretty good for a truck with so few miles and one that weighs about a thousand pounds more.  Looking forward to towing, hopefully later in the summer. 

[samuse]

How are you guys doing it?

 

 I have a '20 single cab dually and so far, unloaded highway is 13mpg.  

 

My 6.0 gas gets almost that??

Edited March 30, 2020 by samuse

[Ray Pickle]

I got more than that with my old 16' 6l. Is it in drive?? JUST KIDDING!! It does sound like a driving style issue though or a driveability issue with truck. I have never heard of anyone with any make or model diesel get 13 mpg on hwy at normal speeds.

[samuse]

I do drive pretty fast.   Highway traffic around here moves at 80-90+.  

 

My '11 6.0 gets 11-12 in the same driving.  

 

This is my first diesel since an '03 Powerstroke.  

 

I heard you were supposed to keep these aired out to keep the emissions stuff working good. Maybe I'm overdoing it??