Lower than expected MPG

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  1. amirza786

    amirza786 Senior Member

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    I see a lot of people are getting between 30 and 40 mpg, but my MPGs seems to suck. I'm averaging between 22 and 25 it seems no matter how I drive. I thought maybe I needed an oil change, but that made no difference. Tire pressure is fine, don't have any performance issues. I am tuned with tsp stage 1 tune but mainly use map 1, no matter which map I use MPGs are about the same anyway. I am stock except performance Cat-back exhaust and Mishimoto Intercooler. Not sure what's going on...
     
  2. arpypat

    arpypat Senior Member

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    I averaged 43mpgs on a road trip from Dallas to KC :D

    City driving is different, though... I feel like the only way to get anywhere close to 30+mpgs is to shift at 3k and use 5th gear for cruising between ~40-50mph. Of course, this then takes all the fun out of it!

    I noticed for highway driving, the best MPGs come from keeping the engine at around 2500rpms in 6th gear, which correlated to ~65mph. Every engine is different.. My TL got the best mpgs cruising in 6th at 75mph.

    My engine is all-stock too, so I can't speak on how an exhaust, intercooler and tune will affect performance/fuel efficiency.
     
  3. quakaroaks

    quakaroaks Member

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    Monitor fuel trims and see if you have an air leak somewhere? A car running lean condition are one of the causes for mpg dip. Hope you find the source of the cause.
     
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  4. OP
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    amirza786

    amirza786 Senior Member

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    I'll put my laptop on it and check the fuel trims when I get a chance but I'm not sure what they should be
     
  5. Jayceegee

    Jayceegee Senior Member

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    I'm getting 38 overall and 43 to 45 on the road using cruise control. Hope you find the solution to your problem
     
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  6. Micah

    Micah Senior Member

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    Avoid boost. Shift at 2k. You will see much better mpg.

    When you want to move, downshift and punch it for a moment. Then get in a higher gear and cruise at 1.5-2.5k rpms in 6th.
     
  7. OP
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    amirza786

    amirza786 Senior Member

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    That reminds me of my hybrid driving brother in law who takes his foot off the gas every chance he gets in his quest for mpg's. There isn't a hill he doesn't like
     
  8. Micah

    Micah Senior Member

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    I have a couple coworkers who drive hybrids. I get the same mpg they do, and I take off like a bat out of hell from the work parking lot daily. Nothing wrong with quickly getting up to the speed limit in first or second before skipping a gear or 3 and cruising.
     
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  9. REBELXSi

    REBELXSi SeƱor Member

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    Gotta do what you gotta do. Most of my miles are on cruise control and I get great mileage.
     
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  10. 69L46Vert

    69L46Vert Senior Member

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    I can get 45 on secondary roads (50 mile trip) without being super careful and only flooring it a couple times. Certain it would be a good bit over 50 on the highway but we only have one highway here in Maine and I haven't been on it yet. One thing I have noticed is that at least on secondary roads, getting the best milage in this SI doesn't always mean being in a higher gear. I have almost never used 6th gear. We don't have the best roads here.

    Disclaimer: Using the car's milage indicator. Have not figured it manually.
     
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  11. SirVicksDeep

    SirVicksDeep Member

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    Just got 40.8 MPG driving 80+ on a work trip to NC but I normally get about 27mpg driving around downtown Charleston SC. All stop and go.

    20190709_150431.jpg

    20190709_100529.jpg
     
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  12. xcivicx

    xcivicx Senior Member

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    any extra pressure on the gas peddle makes mine go down, it is possible to equal the the mpg of the 1.5 engine in the hatch i had, just very unlikely that i can keep the foot off the gas.
    t great mpg seems to end at about 75 mph. as i drive this fast on the interstate, my enemy is a head wind. any decent speed with a head wind and my mpg goes to the dump
     
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  13. OP
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    amirza786

    amirza786 Senior Member

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    On Tuesday I installed a Vibrant resonator to quiet down my 3" performance exhaust, and not only did it quiet things down and make drivability better and more pleasant, but I am suddenly getting good MPG again! For the last 6 months I was getting shitty mileage, averaging between 19 and 23. Since Tuesday after installing the resonator I am averaging between 30 and 38! I have not done anything else. I'm really baffled here...

    MVIMG_20190718_221245.jpg
     
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  14. Jayceegee

    Jayceegee Senior Member

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    " I'm really baffled here " now that's a funny pun !
     
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    amirza786

    amirza786 Senior Member

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    No pun intended...ok some pun intended
     
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