GM Truck Club
Founded in 2004 ~ We're the #1 Chevy Truck & SUV Forum.
Silverado & Sierra | Tahoe & Yukon | Suburban & Yukon XL | SUV & CROSSOVER
Results 1 to 7 of 7

Thread: Need some help

  1. #1

    Unhappy Need some help

    I've got a 2008 Silverado w/5.3 and atrocious gas mileage...13city/17 highway. Ive heard of rechipping these trucks either with something like Bully Dog or the like to improve mileage and performance...anyone have any input on this?

  2. #2


    My friend owns a limo company and said he's tried everything to get better mileage. The performance chips work a little bit on hp and torque, but really don't do much much for gas mileage.

    Proper noun. Used to describe ones large, lifted, comfortable, gas guzzling SUV that is driven primarily in the backwoods. Synonym for Chevy Suburban/ GMC Yukon XL.
    One corporate Suburbanite says to the other, while sipping his overpriced latte, "Check out the hick in that Montana Cadillac!" Both giggle as they wait for AAA to come pull their Audi/ BMW/ Mercedes out of a snow filled ditch

  3. #3


    Check your rear end ratio. You might want to swap it out with the highest ratio available. Go to and download the 2009 Silverado, (no 2008 available). Then search on "ratio".

  4. #4


    The problem with changing the gear ratio is cost balancing, it takes a long time to regain that $750-$900 you'll spend to regear.
    Look at a tire pressures, tire tread style (an aggressive off-road tread decreasses MPG), tire size, unnecessary weight carried in the truck, added exterior items that may increase drag, maybe try using synthetic lubes for decreased friction, and last but not least check your driving style.

  5. #5


    I gained horsepower and torque with my diablo tuner and have also regained my money in gas savings. So yes it will help just have to have it set up right
    2009 chevy 1500 z71 4x4
    2.5 ccm level,2.5 inch rear blocks 305/60/18 coopers stt,Debadged,10 series flow w/dual exit in front or right rear tire, KN CAI, diablo InTune, 18% tint all the way around ,spec-d euro headlights with black housings,winjet smoke LED tail lights,putco LED third brake light smoked, fab fours front bumper with 10k warn winch, RK sports ram air hood
    1965 c10 swb, zz4 350 with the hot cam and fast burn heads and a 780 Holley on top, richmond super street 5 speed,restorod

  6. #6

    Join Date
    Sep 2010
    everett, massachusetts


    I would say you do have a problem. with stock tires/stock height, 4X4 , 3.73 rear gears, 5.3L engine Lt silverado ext cab I get 15-19MPG. 15 around town . 19 on hywy 70 MPH. gasoline 87 octane.

    clean the maf. could be the sensor wires are with a film . use MAF cleaner.

    if the vehicle has larger tires and is with a lift kit then this would be why. also if you use E85 fuel this lowers MPG.

  7. #7


    The cheapest way to improves mpg's is with your right foot. I know because it is also my problem. But as was said earlier a good tune that is done for your vehicle will help. I bought a Diablo InTune and had Lew work his magic and it helped. I gained about 2mpg's with this.

    2011 GMC Sierra SLE - 5.3 - 4X4 - Z71 - King Shock Level Kit - Body Color GMC grill emblem - 2 Tone Engine Cover, Rad Cover and Battery Box - Volant CAI - Tru Cool 40K tranny cooler - Sylvania ZXE bulbs Hi/Low -TriFold Hard Tonneau Cover- CoverCraft Seat Covers - Diablo inTune - GoRecon LED under rail lights - GoRecon LED White Lightning Tailgate Light Bar - Windows tinted to 45%- Kenwood DNX6990 - JL Audio C5-650 &650X- JL Audio Amp- Interco Truxus M/T 33x12.50x18

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts