Duramax mileage

[2018GMC]

nice detailed post CAtaylor. Good info

[Dennis Harris]

If you have a 2015 STAY WITH IT, bought a 2018 3500 Duramax REGRET IT TERRIBLY. The NEW Duramax in the 2018 has crap MPG you can get 20 somedays other days animist days 12. The increased wash of fuel in the cylinders at idle for emission requirement has taken away the fuel economy BIG TIME. Wish I could find the guy that bought my 2015 3500 Dura trade, I'd trade him trucks. Been in dealership 3 times n 8 weeks with 4,100 miles on it. First 1,000 got 20 MPG now it's 12-14 2015 could get 20 all day anyway thru the 130,000+ I drove it. 

[Colossus]

That millage sounds normal to me.  It's what I got in my 2012. 

[Colossus]

Ever since GM and the other manufacturers put the DPF and DEF and EGR crap on there to meet the EPA requirements, the millage has sucked.

[mookdoc6]

22 minutes ago, Colossus said:

Ever since GM and the other manufacturers put the DPF and DEF and EGR crap on there to meet the EPA requirements, the millage has sucked.

Sure, Has the L5P is sucking a tad more gas is what people are telling me especially in town vs there 14.15.16's?  I guess my hopes for Diesel to prevail and land in more drivers hands and loose some of the ill gotten hate from jeesh...early 80's which was warranted. The New 1500's inline 6.........IF GM gives me 300HP and 500+torque with 28mpg's HWY?  Man I could be sold?  Don't twist my arm.....give me minimal emissions troubles butter smooth 10speed....2000.00+ up charge?  Yeah, right!  SOLD or it's 6.2L for me! 

 

Edited April 8, 2018 by mookdoc6

[Tunnelgas]

I have a little less than 1000 miles on mine so far and the onboard says I am getting 15.6mpg.  Those miles are mostly around town though - no interstate trips to offset the stop and go.

[Colossus]

15.6 around town is great!  13 MPG around town with a light foot on the pedal was about as good as I could get on my 12, and about 14.5 MPG around town on my 2008 Dmax.

[gearheadesw]

Wow, all of a sudden the diesel gets just about the same fuel milage as my 6.0 !!?? I get 13 mpg, always,  in my truck.

[redwngr]

The job it's doing / how it's being used can make a HUGE difference in dmax fuel efficiency.

 

At least it always has with mine.

 

They all do the best when run at steady speed, so stoplights and speed variation in town is the enemy. 

Cruise control is a best friend.   

If running unloaded and not towing, and if fuel economy is more important than time, then letting engine run at min speed to stay in 6th will give best efficiency. If find that when warmed up they will shift to 6th somewhere around 52 mph.

This means that 55 will be better than 60, and 60 will be better than 65, etc.

Headwinds, cornering winds and cross winds will mess up any number comparisons.

 

For me some days fuel economy wins and some days time wins. 

 

 

 

 

Edited April 12, 2018 by redwngr

[Silverado4x4]

1 hour ago, redwngr said:

The job it's doing / how it's being used can make a HUGE difference in dmax fuel efficiency.

 

At least it always has with mine.

 

They all do the best when run at steady speed, so stoplights and speed variation in town is the enemy. 

Cruise control is a best friend.   

If running unloaded and not towing, and if fuel economy is more important than time, then letting engine run at min speed to stay in 6th will give best efficiency. If find that when warmed up they will shift to 6th somewhere around 52 mpg.

This means that 55 will be better than 60, and 60 will be better than 65, etc.

Headwinds, cornering winds and cross winds will mess up any number comparisons.

 

For me some days fuel economy wins and some days time wins. 

 

 

 

 

Wow, your get 52mpg when it shifts to 6th? I know I couldn't resist just kidding.

[redwngr]

41 minutes ago, Silverado4x4 said:

Wow, your get 52mpg when it shifts to 6th? I know I couldn't resist just kidding.

thanks....fixed it...

 

(but it will do 25 on flat ground with no wind)

Edited April 12, 2018 by redwngr

[avalonandl]

My mileage has improved as engine broke in.

 

13-15 in town.

Hwy 18-22 depending on speed.

[gearheadesw]

11 hours ago, avalonandl said:

My mileage has improved as engine broke in.

 

13-15 in town.

Hwy 18-22 depending on speed.

 

 

Nice, that's good to hear. I was surprised to see the low teens in this thread for diesel milage.

 

My truck, a gasser, has been getting slightly better gas milage as I pass 10,000 miles, finally braking in it seems.