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8.1 on gas

Discussion in 'Chevy Trucks' started by GMC HD, Nov 27, 2003.

  1. GMC HD

    GMC HD Junior Member
    from CT
    Messages: 10

    just wondering what kinda of mileage others were getting on this engine. i've calculated about 8.5 mpg. just wanted to know if that is normal. i already know big block = big gas.
  2. Foz

    Foz Senior Member
    Messages: 119

    I have 2 2500HD with 8.1 & Allison auto, they get between 8 and 11 MPG depending on what we are doing. The wife's Yukon Xl get an average of 12 MPG with 8.1 & 4 speed auto.
  3. PS496

    PS496 Junior Member
    Messages: 11

    My 2001 8.1/allison 4.10 gears, gets 10.5 in the city and 11.8 on the hwy pulling a 20 ft bass boat.
  4. BigRedBarn

    BigRedBarn Senior Member
    Messages: 133

    I typically get 10-10.5 in the Summer, almost always empty and w/o a tow vehicle. I have yet to hit 11 even though I tried really, really hard once by being "good." I do all mixed driving, but mostly around town in a semi-rural-ish community. Luckily, this isn't my primary vehicle, so I don't spend a lot on gas as I don't drive this truck that much. It's a 2003 2500HD reg. cab & bed, 8100, Allison 5-sp. auto, 4.10's, locking rear diffy, 7½ Western.

    In the Winter with plowing my driveway and a couple of other's driveways, it'll go down to 7-8, which I'm a little surprised at. I typically leave the plow on all Winter (lazy). I also have about 300# of weight in the bed during the Winter (2 layers of old cross arms from utility poles... they're 8 foot long and just right as I wind up w/ a smooth floor in the bed).

    My old 1992 GMC 350 w/ 125K got 2-3 or slightly more in Winter when doing a lot of plowing. So, I'm not disappointed with the new truck.

    I enjoy setting the electronic readout to show instantaneous mileage. "Hey look, we're rolling down a big hill and we're getting 55 MPG's!" Or, "Hey look, we're climbing a big hill and we're getting 1-2 MPG's." I'm surprised at the instant NPG's while plowing aren't as low as I thought they'd be.

    Finally, the electronic readout for average fuel economy, for I assume the entire time since the truck was new (I never reset it that I know of), shows 9.9 MPG.