Sudden Significant Drop in MPG

Discussion in 'Prius v Fuel Economy' started by RGB70, Oct 15, 2016.

  1. RGB70

    RGB70 New Member

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    Anyone else have an issue where the mpg average has dropped significantly? My Prius V 2015 wagon (25500 miles) has dropped from an average of 43-45 mpg to 35 or less.
     
  2. bisco

    bisco cookie crumbler

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    welcome! ouch, that's a big drop. has anything changed at all? commute? tires? tires pressure? oil level, recent service?
    one thing, there is a switch to winter gas blend sometime around now, which can be a 10% hit to mpg's.
    make sure your parking brake is free. put it in neutral at around 20 mph to see if she free wheels okay. be careful, there's a sudden surge when putting in neutral, do it away from traffic.
     
  3. fuzzy1

    fuzzy1 Senior Member

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  4. exstudent

    exstudent Senior Member

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    Has it been colder than normal for a week or more? Colder temps affect MPGs. Winter=worse MPG. Summer=better MPG.

    Maybe your 12V is drained, causing the engine to run more often than necessary? Perhaps a trunk, map, overhead light was left on accidently, causing this drain on the 12V?
     
  5. William Redoubt

    William Redoubt Senior Member

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    It's always possible that you left the car on overnight or for an extended period of time. I often camp in my Prius, and when I do mileage drops from mid 50's to the 30's, depending on the temperature as I leave the car in ready and the climate control in the 70s. The ICE starts occasionally to keep the traction battery charged, consuming fuel.
     
  6. eman08

    eman08 Active Member

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    Lol mine dropped like a roller coaster after maintaining 58ish MPG per fill up. My engine stays on longer as it be like 40 degrees in the morning and 50-60 degrees during the day and back to the 40s at night. Put 5.8 gallons in and nearly at a quarter tank with 190 miles I driven. That's like 34 MPG by hand but my MFD reads 46 MPG. I got to get some engine block heaters.

    Posted via the PriusChat mobile app.
     
  7. exstudent

    exstudent Senior Member

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    Be sure to buy it from PriusChat. Engine Block Heater for 2004-2009 Toyota Prius - PriusChat Shop

    A timer to turn on/off the block heater so only enough electricity is used. Maybe 1-2 hours is enough before you leave in the morning. Otherwise, you'll plug-in when you arrive (say 6PM), and unplug when you leave (say 8AM); 14 hours of electricity, vs just what you need (maybe 2hrs).

    Be sure the timer has a high enough amp rating to support the block heater.
     
  8. Kenny94945

    Kenny94945 Active Member

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    Wow...ours according to the since inception dash computer remains about 41 mpg.
    Lots of variables.
    Here's some ideas:
    a) How is the OP deducing the mpg dropped?
    b) Winter is engine running more of the time?
    c) Change in fuel composition or brands?
    d) More acceleration, different travel routes, other drivers?
    e) Tire pressure un-altered?
    f) Fuel leak....smell any fuel under the hood?
    g) More weight/ luggage/ passengers?
    h) Brake drag? Feel a wheel after a drive; is it hot to the touch?

    Common reasons in my experience: Tire pressure, more uphills/ acceleration, winter fuel blends w/ E85.
    20% drop is fairly strong drop....not sure if that is in a forum member experience A-O-K range.

    Let us know what you discover.
     
  9. bisco

    bisco cookie crumbler

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    have you put a lot of weight on recently?
     
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  10. Sooner Al

    Sooner Al Active Member

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    Oh oh... you got to be careful with statements like that...
     
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  11. eman08

    eman08 Active Member

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    #11 eman08, Oct 18, 2016
    Last edited: Oct 18, 2016
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  12. mikefocke

    mikefocke Prius v Three 2012, Avalon 2011

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    If your variation is based on one tank of gas, the shutoff on the pump nozzle may vary from time to time. I often have wild swings in MPG, low followed by high or the reverse but the average over many fills is remarkably steady.
     
  13. bisco

    bisco cookie crumbler

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    can sometimes be a thyroid thing.:cool:
     
  14. RomaniGypsy

    RomaniGypsy Junior Member

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    Around that time of year, depending upon where you live, gas stations will switch to "winter blend" gasoline. This has less energy per unit and as such, you will get worse gas mileage with it. Further, if you use the heat a lot, that will wreck your mileage. Driving the same way all year (except for when I have to drive in snow), I get about 46 mpg in the summer and 40 in the winter.
     
  15. mrswylie

    mrswylie New Member

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    Ah, a wonderful time in Michigan - done with winter blend, warmer temps but not so warm as to demand A/C. Not hard to see 50 on the trip computer - which means 46-48 in real life.
     
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  16. bisco

    bisco cookie crumbler

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    what happen to the o/p, was it something i said?:oops:
     
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