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MPG difference between 3.08 and 3.42 ratios

Discussion in 'Engine & Drivetrain' started by Tiredmechanic23, Jul 3, 2020.

  1. Tiredmechanic23

    Tiredmechanic23 Full Access Member

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    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.
     
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  2. swathdiver

    swathdiver Full Access Member

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    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.
     
  3. BigtimeBama

    BigtimeBama TYF Newbie

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

    swathdiver Full Access Member

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    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.
     
  5. Tiredmechanic23

    Tiredmechanic23 Full Access Member

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    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.
     
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  6. Texasdaddy

    Texasdaddy Full Access Member

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    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...
     
  7. Christoph

    Christoph Member

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    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: Jul 13, 2020
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  8. Tiredmechanic23

    Tiredmechanic23 Full Access Member

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    seems like a small enough difference I may do the swap then. I am only a 2x4 so that should help a touch.
     
  9. dsh1106

    dsh1106 Member

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    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
     
  10. Bob2C

    Bob2C Full Access Member

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    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
     
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