6.6 Gas MPG

Ray Pickle · May 28, 2020

I cannot find any literature that reads use 93 octane while towing. I don't believe your trucks ecm will make any allowance to maximize any benefits 93 Octane might provide.

See you are from Cincinnati as well, all the best!

Ray Pickle · May 28, 2020

Follow up, I see no mpg difference while towing or unloaded with 93. I do however feel a difference in my wallet. .60 a gallon difference between 87 and 93!

Dunn · May 31, 2020

granted the computer on truck is a joke at calculation and not even close to being accurate.....ill have to fill up next time and physically do calculations but it says i am getting around 16-18 hwy but like 11-12 around town.....thought it would be better but it sure seems like i fill up quite a bit and with 36 gal tank its not too bad now but will be eventually.....and i drive with a light foot most of the time....i thought i would be averaging around 15-16 but more like 12 -13.....still under 2k miles on vehicle so maybe it will loosen up

Dunn · May 31, 2020

i ran one tank of 91 and computer said i got best mileage thru that tank but i don't trust the computer as its great one day and horrible the next....same stretch of road at same speeds.....so one time isn't enough to convince me and i would have to do actual physical calculations......my 2019 RST was same to be fair, computer was all over the map depending on day

it did seem to run a bit smoother on 91 as well but ive always ran 87 and only ran 1 tank of premium so its sure not enough to convince me.....ill try it a few more times with real calcs….am sure its same and only physcological at best

curver900 · June 2, 2020

I just paid 1.45 for diesel and gas was 1.89 I feel like I was stealing ... Mora mn is having some sorta diesel war and I am enjoying it filling my truck up for less than $50 you can't go wrong with a diesel and I got 24.2 mpg on a 50 span going 65 unloaded whooot whhhot but 11 hauling the 9k toy hauler. My calculated mpg has been 20.2 unloaded for 2 tanks combined driving. My regens are at 820 miles so I passed on the update, my shortest Regen was 500 miles with idling and winter fuel

curtis miles · June 22, 2024

My 2024 sierra pro 2500 with the 6.6 gas and allison 10 speed is aversging 11 mpg. Ive had it 1 full year and have driven mostly rural southern indiana. Not bad hills and only about 200 miles with the trailer out of 6600 total. Some in town with traffic lights and such. Im not too impressed wih 11mpg. Heck, my 1985 dodge with the 360 carbed engine git 16. How is it the technology has made it worse?

bruceb58 · June 22, 2024

First long trip was getting 15 to 16 MPG going a steady 70. truck had 500 miles on it.

lineman1234 · June 22, 2024

2024 3500 regular cab 4x4 6.6 gasser.

My absolute worst was when it was new with maybe 1,000 miles on it on a trip, on a 80mph interstate, going 82mph, with a almost dead headwind enough that the wind turbines were making good electric power. So that tank got about 12mpg, hand calculated, winter so the temps were around 15f. Also, that was 10% ethanol fuel 87. No choice up north hear. Best tank to tank so far, with the same type fuel is 16.5mpg, Thats rural roads, calm one day, windy the next, hand calculated. The dash is very close to hand calculated. 11,200 miles on it today, bought 1/23/23.

A person has to come to reality, that the L8T 6.6 gasser is made to work, and like it, alllll day long, every day, for those that dont want or need a diesel but need more than a half ton. Then be a car, that isnt the best on fuel economy, but fun to drive.

I am retired and full time rv it, its my home. I took last winter off, but am back at it with a new to me 5ver and my new cheby. I am coming from a 2500 diesel after 8 years of that. The simplicity of the gasser is refreshing, with its simplicity. All winter hear, way up north in MN, diesel was a solid $1.35 more a gallon, and now its .50-.60 cents more a gallon. So the cost tank to tank is a wash or better, for me and my driving needs and area. I have only towed my 10,000lbs 5ver for 70 miles so far, as it will sit till fall then head south. If i get 6mpg worst ill be happy, if i get 8 mpg or more, that will be a treat. my 5ver is tall with the front added AC unit, so lots of air to catch.

BCGM · June 27, 2024

I have been mostly driving in town so far ,stop and go ,traffic lights ect. seems 17 liters per 100 Kl

Another JR · June 30, 2024

On 6/27/2024 at 10:37 AM, BCGM said:

I have been mostly driving in town so far ,stop and go ,traffic lights ect. seems 17 liters per 100 Kl

Edited June 30, 2024 by Another JR

BCGM · July 1, 2024

On 6/30/2024 at 7:53 AM, Another JR said:

Something to add JR ?

lineman1234 · July 2, 2024

Its terrible.

I did research on what i could find on what i might expect on all the aspects of my 2024 3500 regular cab gasser WT 4x4. Before i got it. I set my sights on being happy if i got a solid 15mpg tank to tank. I get more 1-1.5mpg more, i can live with that.

Not a single problem with it yet in its almost 12,000 miles, I still havent gotten the tailgate recall, and wont go if i get it, as i sealed it myself. Not a drop of noticeable oil usage per oil changes, and i just did the 2nd change.

The darn thing is just so smooth, motor and transmission.

3.5 more months and i can comment on heading south for the winter pulling a simple 10,000lbs 5ver that is tall with the added front ac unit for even more drag.

Another JR · July 2, 2024

5 hours ago, BCGM said:

Something to add JR ?

I initially posted a meme poking fun at your base ten units but decided to delete it.

Another JR · July 2, 2024

I will point out that these trucks are about as aerodynamically efficient as a garden shed, and worse if you have oversize tires and/or a lift. Above 60 the mpg drops fast.