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  1. #1

    Default 99 Silverado 5.3 4x4 gas mileage opinion

    I have a stock(except for drop in K&N filter) 99 Z71 that has been getting 15-15.5 miles to the gallon 50/50 city/highway and the same mileage straight highway doing 80 between Yuma and Tucson, AZ. Is this decent gas mileage for my truck that has 139,000 miles on it? I got 14-15 miles per gallon towning a 4x8 Uhaul from Jacksonville, NC to Yuma. It just doesn't seem right to only get 1 mile per gallon more without towing something. What's ya'll's thoughts? Thanks

  2. #2


    Yep. Going 80 uses a LOT more fuel than 65. That sounds about right tho. I had an 03 with a 4.8 that got about 15 no matter what.
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  3. #3


    I've got a 2000 Sierra with 129k miles and I used to get about 16mpg (all city). I got some new 6x ply tires and it dropped to 13.5mpg. So what you're getting sounds about right.
    Pete "Cujo" Clark
    2000 GMC Sierra 1500 Z71 5.3L

  4. #4


    The speed and the way you drive is the killer to mpg, my 02 silverado 4.8 gets best 18 mpg (rural) even with my heavy rims and 31" tires. If you went 60/65 mph compared to 80 your mpg would jump up, also aerodynamics and wind resistance is a big factor in highway speeds.
    2002 Chevy Silverado & 1995 Ford Bronco

    02 Silverado: 50K miles, 20" Motto Rims, Flowmaster 50 Series
    95 Bronco: 160K miles, 4" Superlift, 33/12.5/15 Mickey Thompson
    01 Civic: 75K miles, DD

  5. #5

    mfleetwood's Avatar
    Join Date
    Jul 2010
    Denver, CO
    Blog Entries


    Here is a nice thread that may help you gain some additional MPGs.

    Mike (Denver, CO) - 2008 Sierra 1500 Z71 SLE 5.3L 4WD

    SUSPENSION: Rancho 4" Suspension Lift; Rancho RS9000XL Shocks; Rancho Skid Plates; Rancho MyRide Wireless Shock Controller;
    BFG All Terrain KO 315/70/17
    DRIVE TRAIN: 4.56 Gears; Detroit TrueTrac Differential; True Cool 40k Transmission Cooler
    PERFORMANCE: DiableSport Predator Tuner; Custom Tuned by Diablew; Magnaflow Exhaust; AFE Cold Air Intake
    ELECTRONICS: Kenwood DNX6180 Touchscreen; Subthump box w/10" Kicker; Driver Information Center (DIC); Rear View Camera
    ACCESSORIES: Westin Brush/Grill Gaurd; Westin Nerf Bars; Truxedo Tonneau; 20% Tint; Tow Mirrors w/Heat & Signals

  6. #6


    Quote Originally Posted by ChromeSilver02 View Post
    also aerodynamics and wind resistance is a big factor in highway speeds.
    This is key. When I was first considering buying a truck I looked at light pickups for mpg reasons. I then compared their mpg's to full-size trucks and noted there's really not a major difference. Trucks have the aerodynamic properties of a brick simply due to their simplistic, rectangular shapes and it definitely hurts in the mpg department.

  7. #7


    That 4x8 trailer really wont affect your mileage a lot because most of it is hidden in the shadow of the truck, and as others have already pointed out increased speed equals higher fuel consumption. You may get there faster but you'll use more fuel to go the same distance.

  8. #8


    My 02 with a 5.3l 2 wheel drive was getting around 24 mpg on the freeway with the cruise set at 72mph. I only had a k&n filter and a jet power programmer on it. If I did 80mph it dropped the mpg to around 22. If I drive my yukon xl like an old lady I can get 17 mpg in the city, if I drive it like I want to it drops to 13mpg if not less. Most of it depends on how hard you drive it and your rear end gear ratio. After your next fill up try driving like an old lady. Accelerate slowly and coast up to red lights rather than slamming on the brakes. I would be curious to see what the results are. You might squeeze out another 2 mpg

    1995 Silverado 4x4
    6" BDS Suspension Lift-3" Body Lift-Add A Leaf in rear -Trailmaster SSV Shocks-Duel Steering Stabilizer Kit -AirAid Cold air intake-
    4.56 Gears with Detroit Auburn Locker-Pro-Comp Traction Bars with duel shocks-Aluminum Skid Plate Kit-38.5" x 16.5" Mickey Thompson Baja Claws-Constant Dropping fuel gauge

    2005 Yukon XL Jet Power Programmer, Bilstein Shocks, Bilstein rear springs, Helwig Anti-sway bars, EGR Window Visors, EGR Hood Shield, Denali Headlights, Headlight harness upgrade, GE NightHawk Bulbs, White Night Rear lighting system, Russell Braided SS brake lines, PowerStop Brake pads, PowerStop cross drilled and Slotted Rotors,
    2002 Silverado ext cab 2wd (Sold)
    2003 Yukon XL (Totaled)

  9. #9


    Thanks gents for replying to my thread. My dad has an 03 Sierra w/5.3 and 4wd and gets around 18 highway and about the same as me around town. I will look at the link in one of the previous posts. I already drive kinda like a grandma, but not quite as slow trying to save fuel. I'll give everyones tips a try and see how much better my fuel mileage gets. Thanks again.

  10. #10
    Jr. Apprentice
    Join Date
    Nov 2010
    McConnells, South Carolina


    I got an 05 z71 4x4
    stock 4.10 gears

    And I got 18 driving home from Clemson on the interstate. And I get around 14 city. But then again I dont do 80 because thats like 2500 rpms lol

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