Gas mileage

zelmo · May 3, 2020

I picked up my 2020 Denali 1500 last week and the first day I put about 100 miles on it driving back roads. Then I needed to drive about 300 highway miles and since I do like to follow the break-in procedures GM recommends I took it easy. I'm not going to say I kept it under 55 the whole time but I did not run it hard and I tried to vary the speed as much as possible.

I am still on the first tank of gas so I can't calculate the mileage manually but the DIC is saying I am getting 24 to 25 mpg on those highway miles. Can that be right? I never expected the 6.2 to get anywhere near that.

gothp28 · May 3, 2020

I get about the same. Best was 32.7 on 50 mole run. But I had a loaner with the 5.3 and in was hard to get near 20. Avg 17 or 18. Glad I got the 6.2L.

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eppieguy · May 3, 2020

Use the 400 mile average selection, you’ll get a much better idea of what you can expect to get. My best was 18.6, I average in the 15’s.

smrr1 · May 3, 2020

The numbers shown in the dash are to be taken with a grain of salt. They show a very skewed version of mpg. People might get 25 or even 30 for a short period of time in the right conditions but no chance in hell of that being a real number reflecting what the truck gets as an average. I have seen low 20s myself with a 6.2 AT4 but when i filled the tank up the avg was much lower.

zelmo · May 3, 2020

20 minutes ago, smrr1 said:

The numbers shown in the dash are to be taken with a grain of salt. They show a very skewed version of mpg. People might get 25 or even 30 for a short period of time in the right conditions but no chance in hell of that being a real number reflecting what the truck gets as an average. I have seen low 20s myself with a 6.2 AT4 but when i filled the tank up the avg was much lower.

I understand that but I was asking about mileage on the highway at approx 60 mph, not the overall average. I like to know what the mileage is in specific conditions.

smrr1 · May 3, 2020

On 5/3/2020 at 9:48 AM, zelmo said:

I understand that but I was asking about mileage on the highway at approx 60 mph, not the overall average. I like to know what the mileage is in specific conditions.

Got ya. At least you know the difference! Its neat to see those numbers but i think some people actually think that is what their truck gets all the time!

Edited May 5, 2020 by smrr1

iammrrush · May 3, 2020

I get around 18-19 mpg at 60 mph but if I go up to 80 mph the average drops to about 15 mpg

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zelmo · May 3, 2020

20 minutes ago, iammrrush said:

I get around 18-19 mpg at 60 mph but if I go up to 80 mph the average drops to about 15 mpg

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That is another reason I like to know the mileage under specific conditions. It lets you determine where you want focus - economy or speed.

xsquid · May 3, 2020

2020 RST 5.3. Do 80 on the highway mostly. Seeing around 17.3 with some back road driving. Truck goes 80 so smoothly down the highway. Plus I have the stop start disabled. I guess you really have to stay around 65 mph if you really want to get the best mpg. I know when I had the leather seats installed. They took the truck like 60 miles round trip. Must have babied it had some insane MPG. Sorry just not my style. Although I do love the MPG compared to my 2009 5.3 with the hypertech 93 program. Ordered the Rotofab intake. Like to see if there 2 mpg increase is for really. Either way it should be a nice improvement.

Edited May 4, 2020 by xsquid

Bryant_Olson · May 4, 2020

On 5/3/2020 at 9:50 AM, smrr1 said:

Got ya. At least you know the difference! Its neat to see those numbers but i think some people actually think that is what there truck gets all the time!

Lol, yes it sure seems like they do judging by some of the posts you see on here

wizard4878 · May 4, 2020

there are several fuel milage apps you can download on your phone that work great, as long as you remember to input the miles and gallons. My 2019 5.3 has 24,000 miles and its averaging 21.3 lifetime

Gangly · May 4, 2020

5.3 Z71, CC, SWB w/ 8 spd auto and DFM

I set the cruise control on 70 and got 21+mpg on my last 1,000+ mile trip.

However, you can adjust the parameters that your vehicle uses to calculate avg MPG within the settings on your dash. I'm probably mistaken on the available values, but if I remember correctly you can have the average shown on your dash be an average of the last 25 miles, 50, 10, 250, etc up to about 400 or 500. I set mine to the highest value possible for the most accurate average MPG.

Edited May 4, 2020 by Gangly