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Advice on fuel economy for my new used 2010

Discussion in 'Gen 3 Prius Fuel Economy' started by Cynthia Rea Clute, Dec 6, 2021.

  1. Cynthia Rea Clute

    Cynthia Rea Clute New Member

    Jul 17, 2021
    2010 Prius
    The bottom line:. My new-to-me 2010 Prius is not getting the mileage it should. It is averaging 35-40 according to the monitor, better on the freeway. I observe that, according to the monitor, the ICE is on virtually every moment that I have my foot on the gas, even at low speeds in town, even when the car is warmed up. I also observe that the battery stays almost fully charged at all times. It stays at one bar below full almost always. I have had the the 12v battery checked and it is reportedly fine. I have not yet had the traction battery checked. I am not having any other issues - starts and runs fine. My in-town mileage is mostly very short trips (1-5 miles), and I know to expect poor mileage and ICE always on for those, but even longer in-town trips I have the same experience. My tire pressures are ok, the weather is mild (Seattle). Car has 85k miles. Carfax says it lived most of its life in Portland OR and was maintained regularly at the dealer. Any ideas? Should I suspect the traction battery?
    bisco likes this.
  2. sam spade 2

    sam spade 2 Senior Member

    Mar 31, 2018
    2017 Prius c
    I think you should suspect that what you are seeing is "normal" for that car and your driving habits.
    And gas mileage often suffers a bit as winter approaches.
    Tire pressure can go down a bit.

    I know it is a different model but my C will run the engine any time that it NEEDS any more than just a tiny bit of energy to maintain speed and certainly to accelerate any at all. This means that the engine NOT running is the exception and not the rule.
    IF you can find a long flat stretch of highway with light traffic, you can test this yourself.
    There should be an "energy monitor" screen available to show you where the energy is coming from and going to.

    Sometimes the engine runs just to charge the battery or to keep it up to operating temperature.

    While some of the things you observed can be an early sign of a failing hybrid battery, I think it is WAY too soon to be chasing after that.
    Getting your 12 V battery tested would be a good idea though.
  3. bisco

    bisco cookie crumbler

    May 11, 2005
    2012 Prius Plug-in
    Plug-in Base
    the battery sitting one bar down is very strange around town. on the highway, it can happen. i would definitely get a hybrid battery module readout.
    with the heat off, and engine warmed up, you should be able to drive slowly and watch the battery charge go down, unless your in frostbite falls
  4. fuzzy1

    fuzzy1 Senior Member

    Feb 26, 2009
    Western Washington
    2012 Prius
    Have you done any out-of-town trips, resetting a Trip gauge at the start, to get an MPG for a single 10+ mile highway run?

    The cold rainy weather of the past couple months here doesn't help. Tire model (e.g. models that are not low rolling resistance) and excessive disk brake drag can also contribute.

    Skim this questionnaire for more ideas, though note that it was written for people driving new cars, not older cars that may have accumulated some problems with age:

    Fuel economy complaints/queries? Please copy, paste & answer these questions, esp. if you're new | PriusChat

    If the hybrid battery is staying high more than expected on slow city streets where it is expected fall, I'd more suspect something elsewhere keeping the ICE on too much, not the battery itself.
    #4 fuzzy1, Dec 7, 2021
    Last edited: Dec 7, 2021