How many mpg on 91 octane with/without tunes?
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This is a discussion on How many mpg on 91 octane with/without tunes? within the Engine Modifications forums, part of the Tech & Modifying & General Repairs category; I was browsing youtube to listen to some exhausts for my 2011 wrx 5door and I ran into a video ...

  1. #1
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    Jan 2011
    Rowland Heights, CA

    How many mpg on 91 octane with/without tunes?

    I was browsing youtube to listen to some exhausts for my 2011 wrx 5door and I ran into a video of a guy who claimed to be getting 33mpg highway with just a muffler delete, gutted downpipe and a stage 2 tune. If I really baby my stock wrx, I can get 23 mpg at the most on 91 octane. This seems very low to me. Is there something wrong with my car or the mpg calculator? How many mpgs are you guys getting, interested in various stages of tuning.

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  3. #2
    Moderator rage-wrx's Avatar
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    Aug 2010
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    Don't trust the mpg calculator.The paper pencil method works best.

    With the a/c running I used to get about 22 mpg.Now with a stage 1 tune I get about the same,not much of a difference noticed so far.
    2011 WRX
    2012 FXT

    The Big 2011/2012 Mod Thread

    Ooh,hang on. That is the throb of a turbocharged flat four engine. A sound which,all over the world,heralds the imminent arrival of a moron - JC.

  4. #3
    Moderator Donkey's Avatar
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    There are a lot of variables that come into play with MPG's. Tuning only helps Openloop fueling. Closedloop fueling is always going to target a 14.7:1 AFR. Tire pressure/width,vehicle gross weight,oil type,ambient temps,atmospheric pressure,ethenol % in gas (notice the pumps say "up to 10%",the more ethenol present in the gas the worse your mpg) can all affect gas milage.
    Resident Adviser @ WTF Tuning, LLC
    2002 FORESTER S
    1998 FORESTER S

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  6. #4
    Registered User SKI.WRX's Avatar
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    Jun 2010
    On 91 I have been consistently getting 29mpg on the highway with no AC and my ski racks on. My car is stock besides catless up-pipe and silencer delete. with AC on I have been averaging around 27mpg but I do almost no city driving.

    As for the mpg calculator I recently drove from Colorado to Mt. Hood Oregon in my friends Outback. At our first gas stop the calculator said 22.8 mpg but pen and paper said 24.3.

  7. #5
    Registered User patrickfromnm's Avatar
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    Sep 2010
    New Mexico
    on my stock '11 the best i have done on 91 was about 29 mpg (highway). in town eh like 24 or so.

  8. #6
    Registered User brbauer's Avatar
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    Sep 2009
    White Marsh MD
    You must have a heavy foot b/c I get 25 MPG (about 50/50 highway vs city) in my 09 wrx (stock). I have been on road trips where I have gotten 30 MPG too.

    Regarding the MPG calculator in the car....every once in a while I'll compare it to the pen and pencil calculation, and normally it's within .5 MPG.
    2009 WRX 5 door White - "wht out"
    1998 VW Passat 1.8T Black - blown engine
    1988 Porsche 944 Black - sold
    1999 Honda CBR 600 - sold

  9. #7
    Boost > NA itWRXjustfine's Avatar
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    Aug 2009
    Fort Riley
    +1 for Mt Hood, love snowboarding there.
    2004 Impreza Outback Sport - Sold
    2004 WRB WRX - Sold
    2006 SGM WRX - 400AWHP - Mods

    My 2006 Build

  10. #8
    Registered User kcwrxfan's Avatar
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    Jun 2011
    Shawnee, Kansas, United States
    I get about 23mpg. highway and city combined, shows 21.4 since I have had the car on trip B since I don't reset it,(3000miles so far) but I'm heavy on the gas at times too.
    2011 WRX Limited Stage 3 TP Stinkeye Mob #93

  11. #9
    Registered User mudferret's Avatar
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    Aug 2009
    To get 33 mpg you have to try really really hard, stock or modified, completely defeats the purpose of getting a tbe and a tune. The driver is the most important factor in mpg.

    Sent from my GT-I9100M using Tapatalk
    MMVI WRX - VF43 Airboy Tuned @ 3500'

  12. #10
    Registered User twister8008's Avatar
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    Aug 2011
    Doesn't that defeat the reason of a Rex? Buy a civic si if you want a balance of performance and mpg. I was consistently above 30 mpg.... But then.... It looks like a Civic! :P
    Yellow lights mean go faster!!!

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