MPG difference between 3.08 and 3.42 ratios

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Tiredmechanic23

Full Access Member
Joined
Sep 19, 2019
Posts
192
Reaction score
126
I can pull 25mpg highway out of my 2016 with the 3.08 ratio but im curious what people are getting with the 3.42s. I tow from time to time but I also would like the little extra get up and go. 8 months out of the year my town is flooded with traffic heading to the beaches etc and that extra umph would be great to get though traffic with all the lights we have and get to my side routes to avoid traffic. I travel enough long distance though that mileage does matter to me to a degree.
 

swathdiver

Full Access Member
Joined
May 18, 2017
Posts
19,100
Reaction score
25,029
Location
Treasure Coast, Florida
I can pull 25mpg highway out of my 2016 with the 3.08 ratio but im curious what people are getting with the 3.42s. I tow from time to time but I also would like the little extra get up and go. 8 months out of the year my town is flooded with traffic heading to the beaches etc and that extra umph would be great to get though traffic with all the lights we have and get to my side routes to avoid traffic. I travel enough long distance though that mileage does matter to me to a degree.

I'll bump this and hope some guys with direct experience chime in. I have seen on the pages of this forum fellas reporting nearly the same, 23 MPG with Yukon XL Denalis.
 

BigtimeBama

TYF Newbie
Joined
May 27, 2020
Posts
1
Reaction score
1
I'll bump this and hope some guys with direct experience chime in. I have seen on the pages of this forum fellas reporting nearly the same, 23 MPG with Yukon XL Denalis.

I get 24 hwy and about 18 around town in a 2015 Suburban with the 3:42
 

swathdiver

Full Access Member
Joined
May 18, 2017
Posts
19,100
Reaction score
25,029
Location
Treasure Coast, Florida
I get 24 hwy and about 18 around town in a 2015 Suburban with the 3:42

That's great. The mileage these trucks get has piqued the interest of my father. You see he drives a little Kia Soul that averages 24 mpg on the highway and barely has room for all of my mother's luggage for when they travel. They are both still healthy enough in their 70s to climb into my truck so now owning one of their own might come to fruition.
 
OP
OP
T

Tiredmechanic23

Full Access Member
Joined
Sep 19, 2019
Posts
192
Reaction score
126
That's great. The mileage these trucks get has piqued the interest of my father. You see he drives a little Kia Soul that averages 24 mpg on the highway and barely has room for all of my mother's luggage for when they travel. They are both still healthy enough in their 70s to climb into my truck so now owning one of their own might come to fruition.


That is all those little Kia Souls get? wow im shocked. With such low mileage plus they are known to fall apart and devalue super quick they are almost not worth the metal they are made with.

These SUVs do great for mileage for their size. I have the AFM off with my tune and I imagine with it on plus the tune I could get better than 25 by a couple MPG. But I have the power to tow when I need to for what towing I do plus plenty of room for my 4 kids and all their junk for beach trips etc..

I know they are pricey but if they can afford one or a good used one that was properly serviced they would love it I am sure.
 

K2 Kaiju

Full Access Member
Joined
Feb 17, 2015
Posts
641
Reaction score
636
Location
The Depths
Im about 20-21 on hwy, but I did trim the chin, add the esky mirrors, and leveled it a bit; maybe the burb is thirstier, although I generally drive around 85...
 

Christoph

Member
Joined
Aug 4, 2019
Posts
64
Reaction score
23
I get 24 hwy and about 18 around town in a 2015 Suburban with the 3:42

I get 22mpg with my 2015 witht the 3.42's....but it's also a 4x4. Seems like anything after 75mph and it uses more fuel at a higher rate.
 
Last edited:
OP
OP
T

Tiredmechanic23

Full Access Member
Joined
Sep 19, 2019
Posts
192
Reaction score
126
seems like a small enough difference I may do the swap then. I am only a 2x4 so that should help a touch.
 

dsh1106

Member
Joined
Feb 16, 2020
Posts
41
Reaction score
18
Location
39.7594° N, 84.1917° W
I have a 2017 Yukon with 308s and a 2017 Tahoe with 342s other than than both are the same. (except trim levels)

The Yukon averages 14 in town and 19 open road, the Tahoe averages 17 in town and 22 open road.

Tahoe has dropped a bit since I bought the Diablo tuner, I'm not sure if its the tune or my modified driving habits.

Hope this helps.
Scott
 

Bob2C

Full Access Member
Joined
Jun 11, 2019
Posts
532
Reaction score
430
Location
Northern VA
I get 15 around town and 24 on highway on my 18 Tahoe 5.3 4x4 3.42 rear AFM off running Diablew 91/93 tune. Transmission and differentials filled with AMSOIL Signature. Don’t know if that makes a difference. Very happy


Sent from my iPhone using Tapatalk
 

Forum statistics

Threads
128,786
Posts
1,805,435
Members
91,766
Latest member
GeorgeC
Top