6.6 Gas MPG

SkidooSteve12 · November 26, 2019

Seeing my truck in the parking lot next to other pickup trucks, I can see why the gas mileage isn't much better because it is so much taller and has a big front end that is pushing a lot of air and taking in a lot of air through the grill. And the stock tires on 20" wheels are huge compared to what we used to run on 2500HD trucks, so that eats up some MPG's and I think that's why some people are getting better MPG's than others. Here is a comparison between sizes and at the bottom what is available for the 2020 HD.

Does anyone else use the aCar or Fuelly app? I have since I bought my truck and here are some screen shots of my info so far. I have noticed that the 2 highest MPG tanks were after I filled up at a different gas station than the cheapest place by me which is a Sam's Club gas station. I am going to have to test filling up at a Shell station and Marathon. We have a Wesco by us which sometimes is the cheapest price.

SkidooSteve12 · November 26, 2019

Had to start a new post to continue adding pictures.

This is a picture of my trip meter which hasn't been reset yet since the truck rolled off the assembly line. It had quite a bit of idling time when I was test driving it and testing how my trailers hooked up to it. It is right on par with saying 13.2 MPG and my aCar app saying overall MPG is 12.5 with the 0.7 MPG difference which is right about what I see the difference is with each tank of gas, varies between 0.4 and 0.8 so far.

Regarding the RPM's at cruising speeds, this is a pic of my RPM's with the cruise set at 55 mph on a flat road. And my 25 and 50 MPG best ratings. I never really thought about the engine using more gas if the engine is running below optimal RPM's. Even at 80 MPH my RPM's are just under 2000 I think in 6th gear.

Ray Pickle · November 26, 2019

Shotgun z71, based on your post regarding your best for 25 mi 50 mi and 400 you are getting good mpg. Those 2 mi. commutes are killing your average as Iam sure you know! Cold engine rich fuel mixtures then early shutdown. I think 12 or 13 mpg on short commutes is the best your going to get

texasnavy05 · November 27, 2019

12 hours ago, SkidooSteve12 said:

Seeing my truck in the parking lot next to other pickup trucks, I can see why the gas mileage isn't much better because it is so much taller and has a big front end that is pushing a lot of air and taking in a lot of air through the grill. And the stock tires on 20" wheels are huge compared to what we used to run on 2500HD trucks, so that eats up some MPG's and I think that's why some people are getting better MPG's than others. Here is a comparison between sizes and at the bottom what is available for the 2020 HD.

Does anyone else use the aCar or Fuelly app? I have since I bought my truck and here are some screen shots of my info so far. I have noticed that the 2 highest MPG tanks were after I filled up at a different gas station than the cheapest place by me which is a Sam's Club gas station. I am going to have to test filling up at a Shell station and Marathon. We have a Wesco by us which sometimes is the cheapest price.

12 hours ago, SkidooSteve12 said:

Had to start a new post to continue adding pictures.

This is a picture of my trip meter which hasn't been reset yet since the truck rolled off the assembly line. It had quite a bit of idling time when I was test driving it and testing how my trailers hooked up to it. It is right on par with saying 13.2 MPG and my aCar app saying overall MPG is 12.5 with the 0.7 MPG difference which is right about what I see the difference is with each tank of gas, varies between 0.4 and 0.8 so far.

Regarding the RPM's at cruising speeds, this is a pic of my RPM's with the cruise set at 55 mph on a flat road. And my 25 and 50 MPG best ratings. I never really thought about the engine using more gas if the engine is running below optimal RPM's. Even at 80 MPH my RPM's are just under 2000 I think in 6th gear.

Great write up. I'm going to start using fuelly.

I wonder what the difference is between the trip mpg and hand calculated mileage? Does the DIC exclude fuel burned while idling? My DIC is also consistently higher than hand calculated.

SkidooSteve12 · November 27, 2019

14 hours ago, texasnavy05 said:

Great write up. I'm going to start using fuelly.

I wonder what the difference is between the trip mpg and hand calculated mileage? Does the DIC exclude fuel burned while idling? My DIC is also consistently higher than hand calculated.

Thanks. I used Fuelly's website before when I had a 45 minute work commute one way. Before that I made a spreadsheet that I would fill out after each fill up. lol Yeah I like keeping those kind of stats. Engineering mind always going overboard LOL

Some say their DIC matches their hand calculated MPG, but most people will agree that it doesn't match up correctly. Not sure why.

Ray Pickle · December 2, 2019

Ok, just returned from first road trip. Cincy to Nashville and back 675 mi. Including a short amount of city driving, less than 20 mi., I hand calculated 16.2 mpg rainstorm on way down cut mileage noticeably according to DIC. It was showing 16.6 prior to rain during first 50 or 60 miles on trip down but dropped to 15.9 in subsequent 200 miles. Rained coming back for majority of drive as well. I think it cost me a solid 1 mpg. But pure speculation, educated guess!

greatmizzou · December 3, 2019

I got my computer to eek out 20.0 mpg on the dot for 50mpg average. Interstate plus some county highway travel rolling hills.

was suuuuper gentle on the accelerator, would take advantage of downslope and coast up hills as light as possible. 59mph looked like the sweet spot for highest mpg.

SkidooSteve12 · December 3, 2019

13 hours ago, greatmizzou said:

I got my computer to eek out 20.0 mpg on the dot for 50mpg average. Interstate plus some county highway travel rolling hills.

was suuuuper gentle on the accelerator, would take advantage of downslope and coast up hills as light as possible. 59mph looked like the sweet spot for highest mpg.

What size tires do you have?

ShotgunZ71 · December 3, 2019

Had another trip with the 5th wheel over the Thanksgiving holiday. Somehow, I averaged 8.0 mpg on the trip home. Usually is around 7.5 so far in various types of traffic and roads.

cmysstailights · December 3, 2019

Dam, i average 6.5 towing tt 10k lbs on e85. Was hoping that motor would be doing atleast 9 or maybe 10. Really feel the new trucks need bigger gears.

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greatmizzou · December 3, 2019

1 hour ago, SkidooSteve12 said:

What size tires do you have?

18" LT275/70 R18E

I had to really take it easy to get it that high, people behind me if there were any would not have been happy lol.

More realistic gentle driving is 15mpg average mixed highway use. Straight highway probably 17mpg

magnum74 · December 3, 2019

If they're able to add 1mpg to this truck with such noticeable size, power and capability increases they've done a phenomenal job in my book. The stats on the new 2500 make my 2016 look like a toy.

ShotgunZ71 · December 3, 2019

6 hours ago, cmysstailights said:

Dam, i average 6.5 towing tt 10k lbs on e85. Was hoping that motor would be doing atleast 9 or maybe 10. Really feel the new trucks need bigger gears.

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My previous TT was 9500 lbs and I averaged 8.5 running 87 octane. If you're getting 6.5 running E85, I'd say that's pretty good. A lot has to do with terrain, speeds towing, etc. E85 is good for making power, but crap for getting good mileage. I believe @Cowpie runs E85 almost all the time on his 6.0 and could be a better source for the power/mileage of E85.

cmysstailights · December 4, 2019

My previous TT was 9500 lbs and I averaged 8.5 running 87 octane. If you're getting 6.5 running E85, I'd say that's pretty good. A lot has to do with terrain, speeds towing, etc. E85 is good for making power, but crap for getting good mileage. I believe [mention=122677]Cowpie[/mention] runs E85 almost all the time on his 6.0 and could be a better source for the power/mileage of E85.

Towing in the mountains upstate ny. I have average 3mpg less than 87. Looking to go diesel now

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ShotgunZ71 · December 4, 2019

2 minutes ago, cmysstailights said:

Towing in the mountains upstate ny. I have average 3mpg less than 87. Looking to go diesel now

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I can see where that makes a big difference towing. If I were towing more in the mountains, I may have contemplated a diesel again. We tow the 5th about 10 times a year, with 9 of them non-mountains. Some rolling hills, but not too bad. With the gasser, you can let it churn (manually, if needed) in the 3-4k range and be fine in the hills. Sure, your mileage may be less, but you'll be able to maintain with traffic. How do you drive the truck normally? Short trips, mountians, etc? I have a lot of short trips, also, so the gasser was a perfect fit for my needs and uses. Also saved a little money in the process. I had a Duramax and really enjoyed it, but I didn't really work it all the time like they need these days. For where I go and what I do, the gasser does great.