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

[airwolf912]

2020 AT4 is averaging 20-21 plus highway at 75mph.   Best is 35.7   The story for best is Laramie Wy. to Cheyenne Wy. all down hill for 60 plus miles.

[TackleBox]

My new 2020 2500HD Duramax only has 193 miles on it.  95% or more has been stop and go city driving and the computer is reading 9.8 mpg. I am sure it’s my driving as I am enjoying the torque!  I will be taking it easy to see if I can get the 12 to 14 mpg city (Real world, calculated) I was getting on my 2016 Duramax.  

[Njmurvin]

During my break-in period, I drove about a 250 mile round trip to get my 5th wheel hitch. I kept the speed under 60 which is a real challenge for multiple reasons. I was amazed that I was able to achieve close to 30mpg on that trip. I knew driving at lower speeds made a difference in fuel economy.  I just didn't realize it made THAT big of a difference. I was brought back to earth when I towed my 5th wheel up to Big Bear Lake where I averaged about 10-11mpg (closer to 9 up the mountain).

[Colossus]

Indeed, I too was surprised with how little 2-5 MPH could make in fuel economy. 

[shadow gray 2020 hd]

Easily doing better than 20 on highways, most the way home with it from the dealer it was averaging around 21.9 cruising around 78 .  Average now with some sitting in traffic and some stop and goes has been better than 16.  Have a little over 800 miles on it.  Much better than my old 98 3/4 ton that has a 350, that thing gets about 13 at best regardless of driving style.  

 

Pretty impressed at this point with how effortlessly and quickly this 8000+ lb truck gets to cruising speeds.

[2011Chevy]

My truck (3” super lift on 37’s) has less than 3k miles on it.  So far every tank has averaged 15.5-16.5 mpg hand calculated and numbers taken into account for mileage discrepancy due to the larger tires.  The only tank that saw less than that was towing a tandem axle utility (12.5mpg) for about 80% hwy at 70-75 and 20% two lane back roads.  I’m pretty happy with these numbers considering the size of the truck and the tires and lift.  

[sealberta]

I noticed a big change in MPG after 5000kms.  Was 14.5 to 15 l/100km city (15.5 to 16), now 12.5 to 13 (18 to 19).  Highway was 12 to 12.5 (15.5 to 16), now 10.5 to 11 (21 to 22).  

[BigKahuna]

I test drove a CCLB SRW Denali today, got 22mpg on a 30 mile loop, speeds mostly 50-65mph country roads and highway. My 2019 1500 High Country with 6.2 gas I pre-ran the same loop, same conditions and driving habits and got 25mpg. Start and finishing points the same, blah blah blah, it was as controlled of a test as one can do. My lifetime average with the 1500 is 19mpg hand calculated, I typically get 15-16 around town and 21 highway And DIC is deadly accurate.

 

That being said I put 91 octane in the 6.2 which costs 25% more than diesel around here at the moment. I was hoping for slightly better with the duramax but my expectations may have been unrealistic. I signed the deal, trading it in.

Edited September 19, 2020 by Camstyn

[Colossus]

You won't see 25 MPG in an HD Duramax.  19-22 MPG is more realistic for highway at 65 or under. 

 

Edited September 19, 2020 by Colossus

[OhioDave]

Crossed 30,000 miles this week.  Unloaded driving 60 mph on long, flat highway with no wind......25 mpg

at 72 mph.....22 mpg 

 

combo cityhighway ......19.0 mpg

 

once winter fuel arrives, take 10% off those figures 

Edited September 24, 2020 by OhioDave

[BigKahuna]

2 hours ago, OhioDave said:

Crossed 30,000 miles this week.  Unloaded driving 60 mph on long, flat highway with no wind......25 mpg

at 72 mph.....22 mpg 

 

combo cityhighway ......19.0 mpg

 

once winter fuel arrives, take 10% off those figures 

Those are great numbers. What spec is your truck? Stock tires?

[Lfod1836]

High country Standard bed all stock.

Flat land south Texas 65 mph for 120 mile loop.

Hope this holds!!