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Lousy mpg over 100k miles 2010 Prius

Discussion in 'Gen 3 Prius Fuel Economy' started by mikeflores2000, Oct 2, 2020.

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Has your mpg dropped significantly after 100k miles?

  1. Yes

    2 vote(s)
    20.0%

  2. No

    8 vote(s)
    80.0%
  1. mikeflores2000

    mikeflores2000 Junior Member

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    2010 Prius
    Model:
    IV
    I purchased new a 2010 Prius 3rd gen when
    Mpg was 50.

    Gas consumption terrible after odometer reaches 100k miles. Have you experienced same fuel efficiency drop?

    2020

    08-24 176927 30 mpg 8 gallons Costco

    08-12 176684 29 mpg 8.3 gallons Costco

    07-30 176445 35 mpg 7.3 gallons Costco

    07-21 176187 6.3 gallons mpg 27 Costco

    07-09 176018 8.2 gallons mpg 32 Sinclair

    07-01 175755 4.5 gallons mpg 29 Loves

    06-25 175625 44? MPG 6.23 gallons Costco

    06-16 175510 49 MPG

    06-12-2020 175353 47 MPG
     
    #1 mikeflores2000, Oct 2, 2020
  2. Grit

    Grit Senior Member

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    Not yet. Last week's tank was 67.1 mpg @ 157,000 miles. Depends on driver's driving style, distance per drive & maintenance.

    IMG_3111.JPG miller cat
     
    #2 Grit, Oct 3, 2020
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  3. jerrymildred

    jerrymildred Senior Member

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    WOW! Something sure went sideways back there in late June. Dragging brakes? Failing traction battery? New tires not LRR? Lots of other possible causes.
     
    #3 jerrymildred, Oct 3, 2020
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  4. mikeflores2000

    mikeflores2000 Junior Member

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    Good catch jerrymildred. Traction battery replaced June 11, 2020 and mpg went from bad to worse.
    My 2010 Prius was purchased new and mpg was near 50 mpg. Since odometer passed 100k mpg nosedived made worse with a refurbished traction hybrid battery installed. Attaching photos. Refueling today at Merced’s newest Arco gas station with new storage tanks and clean premium gas. Could be fuel injectors damaged or bad transmission.
     

    Attached Files:

    #4 mikeflores2000, Oct 3, 2020
  5. bisco

    bisco cookie crumbler

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    refurbished says it all. why not get a new one?
     
    #5 bisco, Oct 3, 2020
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  6. Raytheeagle

    Raytheeagle Senior Member

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    Looks like a local company to me :cool:.

    A decent fee for the swap too:(.

    Doesn't appear that longevity will be on the OP's side:whistle:.
     
    #6 Raytheeagle, Oct 3, 2020
  7. Vman455

    Vman455 Senior Member

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    "AVG. 14 MPH": How many of your trips are less than 5 miles? Did you have a life event at the end of June (retirement, change jobs, move) that changed your commute? If nothing changed, I would suspect the refurbished battery first.
     
    #7 Vman455, Oct 3, 2020
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  8. royrose

    royrose Senior Member

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    I have a 2010 IV with 100,000 miles but with a very different experience. My mileage has slowly decreased over time but is still overall in the 40's. The vehicle runs perfectly. No indication of a failing battery.

    I'd suggest getting an OBDII bluetooth enabled adapter that plugs into the diagnostic port under the dash. Then run the Dr. Prius App to assess the health of the refurbished battery. If that battery is under a warranty, you may have a case to have it replaced.
     
    #8 royrose, Oct 3, 2020
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  9. cnc97

    cnc97 Senior Member

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    I suspect that the thermostat has failed. It probably stuck open and ICE not achieving full operating temperature. Or failing 12v battery. Check the 12 v health and see what it’s doing voltage wise after setting overnight. I only drive my high mile 2010 5-6 minutes per trip and I’m still in the mid to high 40’s for MPG. Mine were down to the high 30’s a couple months ago, but replaced thermostat and they recovered to their current level.
     
    #9 cnc97, Oct 4, 2020
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  10. badbrakes1998

    badbrakes1998 New Member

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    I drive a 2010 with 150k miles and get about 38-42MPG depending on the trip. I had a caliper stuck closed and changing it increased MPG.
     
    #10 badbrakes1998, Oct 7, 2020
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  11. SFO

    SFO Senior Member

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    Given the mileage, doubtful. Though in the moment you could spill and fill the ATF-WS, which should prolong the agony :confused:

    If we all need another WAG, let's assume that the 'rebuilder' (used loosely) installed the "degraded replacement pack" after disconnecting the 12v source, then failed to clean the MAF o_O
    Coming from the gen2, this often happens for me. Though it could just be my continued desire for dyslexia as well :cool:
     
    #11 SFO, Oct 8, 2020
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  12. bret kraupie

    bret kraupie New Member

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    If you look at your screen shot to the right your ave. 38 mpg
     
    #12 bret kraupie, Feb 8, 2021
  13. jerrymildred

    jerrymildred Senior Member

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    Oops. You might want to look again. He's averaging 67.1 mpg and 38 mph.
     
    #13 jerrymildred, Feb 8, 2021
  14. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Just cherry-picking: I doubt that’ll improve mpg, just costs more.
     
    #14 Mendel Leisk, Feb 8, 2021
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  15. Rocky Mountain Priusman

    Rocky Mountain Priusman Active Member

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    Seems like checking to make sure the 12v battery is still good (or just replacing outright if it is 5 years old or older) would be first thing I would do.

    Then I'd follow up on the HV battery.

    If both the batteries are good I'd start looking at other possible causes.
     
    #15 Rocky Mountain Priusman, Mar 30, 2021
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