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31 MPG is this for real? 2017 6.2 Denali

wildlyfe200

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Mark Diedrich Enthusiast

Mark Diedrich

Posted
Posted

Yes, definitely with the flow of traffic. In some areas troopers have been known to pull people over and tell them to keep up with the "flow" if they are going substantially slower..... I bet they were surprised by the officer's comment, lol

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Loco-diablo Senior Enthusiast

Loco-diablo

Posted
Posted

A better sampling is to reset the trip odometer and sample a full tank of all around driving. Highway mileage can vary greatly depending on speed, wind and the grade of the highway (amongst other things) 25 miles is too short to determine anything. Absolutely possible to get those kind of numbers or even higher from a 25 mile sample, but it does not represent an overall realistic number.

volcom8190 Enthusiast

volcom8190

Posted
Posted

I get 15 city, average across a few tanks commuting. and 19-21 straight highway over a few tanks on vacation. Hand calculated. the cluster is off by 0.5 in my truck ish.

Marv88 Enthusiast

Marv88

Posted
Posted

I did not buy my truck (2016 5.3L regular cab) for economy however my less than 11 mpg average during non aggressive city driving with lots of stop n go (most of my driving) seems a bit low as does the best of less than 22 mpg on an all highway trip at an average speed of about 65 mph with no load. The service advisor said ithis is normal for "real" mileage but I wonder now after seeing the much better mileage some of you are getting in the larger trucks with larger engines.(?).

I've been running the recommended 89 octane for a while now this time around I decided to try 91 so nice I noticed the truck was idling a little rough. With the vast majority of my driving being stop n go as usual I went from 10.6 mpg avg to 13.0 mpg and no more rough idle. Wondering if the mileage was a fluke/maybe from slightly different driving habit etc or if the higher octane can actually improve mileage but more importantly is it better for the engine?

wildlyfe200 Enthusiast

wildlyfe200

Posted
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I've been running the recommended 89 octane for a while now this time around I decided to try 91 so nice I noticed the truck was idling a little rough. With the vast majority of my driving being stop n go as usual I went from 10.6 mpg avg to 13.0 mpg and no more rough idle. Wondering if the mileage was a fluke/maybe from slightly different driving habit etc or if the higher octane can actually improve mileage but more importantly is it better for the engine?

I have the 6.2 and of course 91 is recommended but you can run on 89 the ECU will automatically adjust the timing and it definitely is rougher with 89 when I 1st bought the truck nobody told me that I ran The 1st 2 tanks with 89 as soon as I put 91 in the rough idle went away in and it drove a lot better. Needless to say this truck will never see 89 octane again while I'm driving it.

 

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Marv88 Enthusiast

Marv88

Posted
Posted

I have the 6.2 and of course 91 is recommended but you can run on 89 the ECU will automatically adjust the timing and it definitely is rougher with 89 when I 1st bought the truck nobody told me that I ran The 1st 2 tanks with 89 as soon as I put 91 in the rough idle went away in and it drove a lot better. Needless to say this truck will never see 89 octane again while I'm driving it.

 

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I figured this much compression/power needed 91 so I used it from new until reading 89 was recommended (which was confirmed by my service advisor) but I'm with you now on sticking with 91.

Loco-diablo Senior Enthusiast

Loco-diablo

Posted
Posted

 

I figured this much compression/power needed 91 so I used it from new until reading 89 was recommended (which was confirmed by my service advisor) but I'm with you now on sticking with 91.

Where did you read that 89 was recommended for the 5.3? The manual recommends (for the 2017 5.3) 87 octane (minimum). I assume the 2016 5.3 is the same?

Marv88 Enthusiast

Marv88

Posted
Posted

Where did you read that 89 was recommended for the 5.3? The manual recommends (for the 2017 5.3) 87 octane (minimum). I assume the 2016 5.3 is the same?

My manual also says 87 "minimum" however I read in a thread here I believe that 89 was recommended and when I mentioned it to my service advisor he said there was no benefit to the 91 I was running but 87 was too low. I do remember trying 87 once out of curiosity and it ran terrible so I never used it again but I'll run another tank or 2 of 91 to see if I am really getting the better mileage (my daughter actually noticed/mentioned the shake was gone while sitting at a stop light so I know I'm not imagining the smoother idle)

Loco-diablo Senior Enthusiast

Loco-diablo

Posted
Posted

My manual also says 87 "minimum" however I read in a thread here I believe that 89 was recommended and when I mentioned it to my service advisor he said there was no benefit to the 91 I was running but 87 was too low. I do remember trying 87 once out of curiosity and it ran terrible so I never used it again but I'll run another tank or 2 of 91 to see if I am really getting the better mileage (my daughter actually noticed/mentioned the shake was gone while sitting at a stop light so I know I'm not imagining the smoother idle)

 

I've been running mostly mid grade (89) since i got the truck, but I never really noticed any issues with 87. The 89 seems to give it a bit more pep and slightly better MPG. We only have 3 grades here in MA. 87, 89 and 93. No 91

  • 3 months later...
CadillacLuke24 Enthusiast

CadillacLuke24

Posted
Posted

Incredible mileage is possible under the right conditions.

 

First week of October 2016, we had 70 mph gusts out of the west, so I did a little experiment. With my cruise set at 70, I got this between Casper and the last turn for Pathfinder reservoir. 

 

7IY0r5F.jpg

 

On the way back, with the wind at my back and the cruise at 70 again, I set my record.

 

CcbhcGo.jpg

 

The other night I drove out to Bairoil for grins, had a 40 mph headwind, and the cruise set to 70. Got 18.5 I believe, not horrible bad. 

On the way back, I set the cruise to 55 since I was cutting it close on gas. It was about midnight, so no traffic. Got this gem.

 

nXScEQw.jpg

 

Sure, these are from the DIC, so some may say these numbers are exaggerated. While that may be true, I'd put my money on the screen connected to the PCM, which monitors both the injector flow rate and hub rotational speed, over any hand calculation. 

Diver6 Enthusiast

Diver6

Posted
Posted

My 16 Max tow 6.2 get 25 mpg average all the time but I’m in Canada and our speed limit is 60, my mileage takes a big hit if I run 70 to 75 in the US. I had a 15 5.3 and the new 6.2 get better mileage!!

ducklawyer Enthusiast

ducklawyer

Posted
Posted

Always surprised with hwy mpg. Even with level and bigger tires. Not the big numbers seen above but still impressive. I have 5.3 IMG_2398.JPG


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redwngr Senior Enthusiast

redwngr

Posted
Posted

2016 5.3 cc   

(fuel meter 'bin size' is different on cdn trucks)

404 mile 23.2

62 mile 29.9

31 mile 36.5 (like others, it was coming out of mountains)

34817 miles 17.4  (includes towing from Port Huron to Phoenix and back at less than 10mpg)

 

Local running, not towing, I'm disappointed when a tankful doesn't average 20 or better.  (20 - 21 range is most common) 

 

I didn't save the data from the 2015 6.2.  It wasn't worse mileage but cost per mile was higher because fuel price.

 

  • 1 year later...
James Howey New Member

James Howey

Posted
Posted

Just bought a used 2017 Denali with the 6.2 earlier this week and took it from Colorado Springs CO to Ogden UT and back and got 37.0 for 25 miles and 30.6 for 50 miles between Laramie WY and Fort Collins CO and 21.7 for the last 400 miles. This was on a cold and windy day doing 75 to 80 on I-80 and dealing with Denver weekend traffic. Granted the stretch from Laramie to Ft Collins I had the cruise set at 68 and it must be a lot more down hill than I thought but by no means is it flat there are some pulls on 285. I was pretty impressed, did a lot better than my 06 Chevy crew 4x4 with the 5.3 ever did on this same run. Hand figured mileage for the entire 1253 mile trip was 20.8 

C4E8EBD4-D666-4426-94BF-7B9249BAE9E6.jpeg

0CD14B4B-3234-42F9-B6A7-9DB73CEF50C2.png

98C4C47A-E5D2-46D0-8EC9-B7C0CE4F64B7.jpeg

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