recent drop in mileage for 2006 Gen 2 Prius

Discussion in 'Gen 2 Prius Fuel Economy' started by Momotaro, Mar 30, 2018.

  1. Momotaro

    Momotaro Junior Member

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    - Have you read This Thead Yet?
    yes


    - What fuel economy are you getting and how are you determining fuel economy? (trip computer or manual calculations)
    I'm basing my conclusion on how rapidly I've needed to fill her up again. Now three times per week. Used to be once per week.


    - What fuel economy are you expecting and why?
    One or two fill-ups per week, as I used to experience.


    - What are the approximate outside air temps?
    Typical PNW temps for this time of year. Hovering near 40F.


    - How long are your trips?
    My commute is 21 miles each way.


    - How much of it is city vs. highway? Roughly what's the average speed in overall and and of each segment? Is there a lot of stop and go driving?
    Stop and go driving? Yes. Nearly all city. Avoid highways around here like the plague. Average speed 30MPH.


    - What region/state are you in? (if you haven't set your location in your profile)
    Washington. Seattle suburbs


    - What's the terrain like of your drives? (e.g. flat, gentle hills, steep hills, etc.)
    Varies. Some hills, mostly flattish.


    - Is your oil overfilled? (i.e. above the full mark on the dipstick)
    No.


    How old is your 12v battery? What is the voltage reading of your 12v battery after sitting over night? (Method Here)
    Not sure. The smaller one? About 6 years old. Had it replaced when it died at that point.


    Have you had your alignment checked? Any pulling or abnormal tire wear?
    Aligned done regularly. No abnormal wear.


    - Are you using the factory tires and wheels? If not, please indicate tire make, model and size (e.g. Goodyear Assurance Fuel Max 185/65R15).
    Buy tires at Costco. The ones that are always on sale.


    - What are your tire pressures?
    Normal.


    - Make, model, year, engine and transmission of previous car? (e.g. 08 Honda Civic Si 2.0L 4 cylinder, manual transmission) What did you actually get on the same trips/commute? (Please give us actual numbers, not EPA ratings.)
    Previous car? In 2006? We drove a 1992 Toyota van (the egg-shaped one). Had a different commute then. Apples to oranges.


    - How are you trying to drive (e.g. trying to stay in electric only?) and how hard are you braking?
    No option to stay in electric only. Brake normally, although hard when traffic snarls unexpectedly.


    - Are you "warming up" the ICE (internal combustion engine) by letting it idle after powering on?
    No


    - Are you driving using D or B mode?
    D


    - HVAC settings? Are you using the heater, AC, auto mode, etc.? If using auto, what temp is it set to?
    Auto set to 70F


    - If reporting a mileage drop, did anything significant change on your car (e.g. accident, hit a curb or big pothole throwing off alignment, oil change/other maintenance/repairs, changed tires or wheels, etc.) or your commute?
    No. I was told it's just getting old.
     
  2. dolj

    dolj Senior Member

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    These are probably two of the most important questions, and you gave nothing answers.

    What specifically are the brand and model of tires and what is the size?

    What are the tire pressures in PSI currently? And what pressures do you aim to use?
     
    #2 dolj, Mar 30, 2018
    Last edited: Mar 30, 2018
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  3. bisco

    bisco cookie crumbler

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    you need to start measuring your mpg's at the pump. unfortunately, since you haven't done that in the past, we have nothing to work with.
    but at least it would give us an idea of how far off 'average' they are.
     
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  4. Momotaro

    Momotaro Junior Member

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    I will figure out what the tires and PSIs are. It's not information at the top of my head. And I had no idea, out of all of the information in that long list, that it was the most critical. I am not a car person. I love my Prius, and want to keep using it for as long as possible. That's why I'm here.

    As for calculating mileage per gallon at the pump...Is that as simple as I think it is? Record mileage at each fillup, record gallons added, and divide the difference in miles by the number of gallons?
     
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  5. bisco

    bisco cookie crumbler

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  6. bisco

    bisco cookie crumbler

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    how many miles on your car?

    how many of those miles have you owned it?

    have you done all the required maintenance, according to the owners manual?
     
  7. dolj

    dolj Senior Member

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    Yes, it is that simple: (Miles at fill - Miles at last fill) รท Gallons at fill = MPG. Therefore you will only get your first MPG at your second fill from when you start your records. So the best idea is to fill your tank now, regardless of how empty it is, and record the milage.
    As it sounds like you do not fill your tires with any regularity, you should fill your tires now to 37 PSI front and 35 PSI rear. Take note of the current PSI of each tire as you fill. After this, make a point to check your tire pressures once a month, anytime there is a big change in weather (large fluctuations in barometric pressure) or large changes in altitude (e. g. you travelled from sea level to 3,000 ft AMSL)

    Report back here with your current tire pressures and the make & model of them, too.
     
  8. Momotaro

    Momotaro Junior Member

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    > yes
     
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  9. bisco

    bisco cookie crumbler

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    sounds like you have a well maintained car then, albeit 12 years old with 190k. once you can nail down the approximate loss in mpg, we might be able to offer some area's to look at.

    how old is your 12v? i see 6 years old. might be worth checking.
     
  10. bisco

    bisco cookie crumbler

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    there are items like throttle body, maf sensor, pcv, that are not in the manual for regular maintenance.
    also, you could have a brake dragging.
     
  11. Momotaro

    Momotaro Junior Member

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    (I have not forgotten about the tire pressure, but I have been able to start calculating mileage after three visits to the gas station in the past three weeks.)

    The calculated mileage numbers are a little variable so far (36.2694 MPG and 42.2078 MPG). I'm wondering how many readings would comprise a decent average...
     
  12. bisco

    bisco cookie crumbler

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    the bladder in gen 2 gas tanks will do that. hard to say how many, i'd be comfortable with 5 or more. plus, is it getting warmer there?
     
  13. Momotaro

    Momotaro Junior Member

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    Getting warmer? Somewhat. It is spring in the Pacific Northwest, and we're finally getting north of 10C.
     
  14. bisco

    bisco cookie crumbler

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    10 Canadian?:cool:
     
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  15. Raytheeagle

    Raytheeagle Senior Member

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    The 49th parallel shrinks from time to time:whistle:.
     
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  16. Momotaro

    Momotaro Junior Member

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    Actually, currently Seattle suburbanite, former Vancouver suburbanite, former Tokyo resident, former rural Massachusetts student, and former New York City suburbanite. Celsius makes sense.
     
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  17. Momotaro

    Momotaro Junior Member

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    After meticulously tracking my mileage for months, I found that the average at 12 years and up to and beyond 200K miles was hovering at the 40 MPG mark. But then my poor Prius died. I suppose that's a topic for a separate thread, but suffice it to say that the dealer I had it towed to said that both the inverter and transmission (transaxle system, probably) were dead. He quoted USD 14K for repairs, at which point I had her towed to my more trustworthy mechanic for a second opinion (which I am still waiting on). In the meantime, we managed to buy a used vehicle. Another hybrid. This time a Lexus (CT 200h). Based on Prius technology, I hear, but definitely a different animal.
     
  18. bisco

    bisco cookie crumbler

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    thanks for the update. sorry to hear it, all the best!(y)
     
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