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  1. #11


    Your numbers are in line with what I get. I have kept track of every tank of gas since new through an app on the iphone and overall the total average including all trailer hauls and everything the average mileage after 38,000 miles is 16.8. If you don't have the DIC--You can add it for $80 and less than 2 minutes of install time it will allow you to see when the truck is running in V4 mode and V8 mode while driving. Plus it keeps track of your average and instant fuel mpg numbers.
    2009 Silverado Z71 4x4 Ext.Cab
    2" Leveling Kit

  2. #12


    I have the stick beside the speedo that allows me to view mileage,oil.change info etc
    If I add the buttons on the side it will allow me to view more without programming?
    It wouldn't seem like chevy would do something that simple. As far as mileage I have got 16 .5
    18.5 and 13.5. Not sure why on the last I just figured it was bad gas.
    Please let me know about the dic panel. Thanks

  3. #13


    Something I had to clarify with a GM mechanic before posting, if you turn off the AFM, or do any programming with a tuner it shows up on the "Logged Entries" in the trucks computer.
    This is a permanent log of all actions that happen that affect the computer, it cant be erased so if you say put a custom tune in and change it back it wont show what the tune was or what exactly you've done but it will show the technician that there was an action completed.
    I'm not sure of what all information they can get from this or if it could be enough to affect Warranty.

  4. #14
    Sr. Mechanic dadngt's Avatar
    Join Date
    Aug 2011
    Poteau, Oklahoma


    I have a 2007 NNBS 4.8 no AFM. Bought the truck bone stock with 21k miles. now have 42k. I was getting best 19mpg. so trying for better, I picked up some alloy wheels new tires still 17 inch just not steel wheels. Added a flowmaster exhaust, new air filter, oil changes when needed. & with those few efforts I'm getting 15 mpg. What maintence is needed at 40k? I have also noticed the tag on the side of the fuel pumps have a -2 rating for the fuel. Used to be in the + side so we're also getting crappie gas.
    Last edited by dadngt; 12-31-2011 at 03:23 PM.

  5. #15
    Sr. Mechanic
    Join Date
    Oct 2011
    Salt Lake City, UT


    Real World mpg from a return trip from Salt Lake City Utah to Southern California-

    Salt Lake to Mesquite Nevada (3 -6,000 foot mountain passes) driving 75 to 80mph= 17.2 mpg (AFM hardly ever came on-to be expected)
    Mesquite Nevada to Southern California driving 70mph w/cruise control on 95% of the time= 21.2 (AFM came on a lot)

    No surprises here - speed kills the mpg and does not allow the AFM to come on.

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