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Mileage starting to degrade.

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Hookitlow, Jan 25, 2020.

  1. Hookitlow

    Hookitlow Junior Member

    Joined:
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    Vehicle:
    2010 Prius
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    II
    My 2010 Prius has 250k miles, and the mileage has been starting to degrade a bit. Mostly it feels like it doesn’t make the same power going up hills. I can at time force it over 50mpg, but it’s settling around 42 instead of 48 during mindless driving. Oil is full, tires are inflated to 39ish, and the 12v battery was replaced a few years ago.

    I recently did all 4 wheel bearings, shocks struts, brakes, rotors, tires and spark plugs.

    I’m now seeing that I overlooked cleaning the egr system.

    it uses some oil, but not outlandish amount. Probably 1-1.5 qt every 5000 miles.

    I’m planning on doing coolant and inverter coolant soon, is there something I’m overlooking?

    I told my wife we can get a new one at 500k but realistically I’m looking to get 100k plus.

    Any thoughts are greatly appreciated.
     
    #1 Hookitlow, Jan 25, 2020
  2. Priuslover09

    Priuslover09 Member

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    It may be the 12v is weak or the engine or hybrid may be weak as well
     
    #2 Priuslover09, Jan 25, 2020
  3. Hookitlow

    Hookitlow Junior Member

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    I was thinking about the hybrid system. It kind of felt to me that the first half of the pedal stroke doesn’t provide the oompf it used to. I wondered about the traction battery, but kind of thought that would affect battery longevity and not necessarily power. Either way I don’t know if I’m down for that sort of expense in this car if it is going.

    can the motor part of the hybrid system just get “tired”? I wasn’t sure if electric motors worked that way.

    I’m going to do the maintenance I can and go from there. Thanks and hope other chime in too.
     
    #3 Hookitlow, Jan 26, 2020
  4. Priuslover09

    Priuslover09 Member

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    You’re welcome?
     
    #4 Priuslover09, Jan 26, 2020
  5. Grit

    Grit Senior Member

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    The only thing I would invest soon is cleaning egr circuit because a lot was already done to keep it on the road, ie struts, tires, brakes & etc. if you both each have a car and commutes are fairly close to each other, then ride the car til it dies.
     
    #5 Grit, Jan 26, 2020
  6. Priuslover09

    Priuslover09 Member

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    I still think there getting there money from the hybrid battery
     
    #6 Priuslover09, Jan 26, 2020
  7. The Electric Me

    The Electric Me Go Speed Go!

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    Looking at your join date, I'm assuming you've owned this vehicle since you bought it?
    So I'm going to say, if you notice a degradation? Then it's really happening.
    Not going to question someone who has owned and operated their vehicle for a long time. You know better than I, if it isn't performing as well as it use to do.

    What I would suggest however, is that given winter fuel blends, winter operating temperatures, and a 10 year old vehicle with 250K on it? The degradation may fall into "normal" or acceptable parameters. IMO, a 6 MPG drop in the heart of winter, isn't necessarily indicative of anything.
    I would probably wait until Spring/Summer and see how much the MPG may rebound.

    The other obvious option, and I'm also assuming when you say "I" that means you DIY this work, is to recheck the work you've done. If the MPG drop coincided with any of this being done, -well if nearly any of those things are "off", it could affect MPG.

    Otherwise just know I'm jealous. I wish I could be upset about getting 42 MPG during the Winter. With my Honda Fit, I can't get 42 MPG during the best of Summer.

    PS.
    If you have the original Hybrid Battery it could be very early signs of it's specific degradation. But again my recommendation would be the same. See how it operates in warmer temperatures. If you aren't getting any codes concerning your Hybrid Battery, I'd just keep driving it.
    Also, what "type" of driving are you doing most? Stop and Go urban? Or highway?
    I might take it on a moderate highway trip, let it warm up and stay at highway speed for a while and see what MPG it is returning under those conditions.
     
    #7 The Electric Me, Jan 26, 2020
    Last edited: Jan 26, 2020
  8. Grit

    Grit Senior Member

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    This could be the culprit. I got new tires myself 2 months ago and suffered 3-5 mpg instant overall lost. Granted my car was getting 63 mpg Overall for the last 12 months so I mentally preplanned for the hit once the previous tires were 2/32” left on treads
     
    #8 Grit, Jan 26, 2020
  9. Hookitlow

    Hookitlow Junior Member

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    I replaced with the same Yokohama avid LRR that I replaced. Problem is I hadn’t really been in the car much before the change, but my wife said the mileage before and after was similar. Seems like the degrade in mileage is over time, not just at the repair.
     
    #9 Hookitlow, Jan 26, 2020
  10. Hookitlow

    Hookitlow Junior Member

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    you are correct, I bought the vehicle new in the fall of 2009. I have a pretty good idea of the summer/winter fluctuation in mileage, this seems outside that, so I do understand it could be due to a quarter of a million miles on the car. I can live with that, but am looking to clean a few things up to try and keep her rolling as long as I can.

    There is some highway, usually not more that 20-30 miles at a clip, with back country roads in between. Not much city driving.

    I’m looking at the 12v battery today. It has a standing voltage of 12.3, and was replaced last in May of 2016, so I’m leaning towards replacing it.
     
    #10 Hookitlow, Jan 26, 2020
    The Electric Me likes this.
  11. Grit

    Grit Senior Member

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    Same. I replaced the tires with an updated model but narrower thinking once the tires break in, it would maybe even yield better MPGs than the previous wider tire.
     
    #11 Grit, Jan 26, 2020
  12. Tim Jones

    Tim Jones Senior Member

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    Clean Intake Manifold
    Clean Entire Plugged EGR System
    Install Oil Catch Can
    Change Trani Fluid
     
    #12 Tim Jones, Jan 26, 2020
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