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Mileage dropping and dropping and....

Discussion in 'Gen 2 Prius Fuel Economy' started by Rxmxsh, Apr 14, 2012.

  1. Rxmxsh

    Rxmxsh Member

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    Fort Worth, Tx
    Vehicle:
    2007 Prius
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    N/A
    - What fuel economy are you getting and how are you determining fuel economy? (trip computer or manual calculations)

    In the last 2 years, I've gone from a solid 47MPG to now an avg of 41.7MPG. I have an excel sheet from day 1 (mile 0) of ownership. Lately, I've been getting 38-40 (last month or so).

    - What fuel economy are you expecting and why?
    I'd expect around 44-45 based on travel time, etc.

    - What are the approximate outside air temps?
    Varies from 50s up to 80s

    - How long are your trips?
    15-30 mins

    - 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?
    90% highway. Smooth, not that much stop and go.

    - What region/state are you in? (if you haven't set your location in your profile)
    SoCal

    - What's the terrain like of your drives? (e.g. flat, gentle hills, steep hills, etc.)
    Surprisingly pretty flat

    - 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)
    Just changed the battery less than a month ago (2 tanks ago). Mileage is unaffected

    Have you had your alignment checked? Any pulling or abnormal tire wear?
    Yes; No

    - 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).
    Yes.

    - What are your tire pressures?
    42/40

    - 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.)
    What? Irrelevant, lol. ;) It was a Camraro, but that was nearly 6 years ago.

    - How are you trying to drive (e.g. trying to stay in electric only?) and how hard are you braking?

    Without thought; easy and gently. :)

    - Are you "warming up" the ICE (internal combustion engine) by letting it idle after powering on?
    Heavens, no. From day 1 - on, and drive.

    - Are you driving using D or B mode?
    No. I'm using D as in 'boy'. Kidding. Only D.

    - HVAC settings? Are you using the heater, AC, auto mode, etc.? If using auto, what temp is it set to?
    Very rarely. When the AC is on 78. Heat 76. But it's usually off. I do understand the impact of milage, but again, it's very rare that the AC/heater is on.


    - 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?

    I bought new tires at the beginning of the year, and I hit another drop. I figured this would go up slowly, but it hasn't yet. Tires aside, my mileage has been steadily decreasing over the last 2 years. We moved, but we moved back to the same area and commute than I was achieving 44-45 MPGs.

    I'm stumped. Please interrogate me.
     
  2. cwerdna

    cwerdna Senior Member

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    Thanks for answering!

    Well, your commute has changed twice. How long is it now in time and distance? What about the two previous ones? How fast are you going on the highway?

    So, you're still running the same make and model of tires that came originally w/your car?

    As for previous car, it's not irrelevant for many. Many people complain about the mileage and yet have no idea what they got on their previous car (and we have no idea what make and model it was). We can at least compare what they got w/their old car vs. its EPA estimates vs. Consumer Reports results, as a baseline. Sometimes they might make a claim that their old car got "xx mpg" when in fact it's virtually impossible given what they describe as their commute. When you dig around, you find out they're reporting an EPA estimate. Often, the poster never returns to answer our questions or report on their results.
     
  3. Rxmxsh

    Rxmxsh Member

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    Thanks.

    Commute 1 - 15 minutes, mostly flat - about 5 miles
    Commute 2 - 34-50 minutes, 90% freeway. Going from high to low elevation - about 18 miles
    Commute 3 - 15 minutes, mostly flat - about 8 miles. I avg about 60 MPH in the am, with a peak of about 75MPH. But based on prior tanks, and knowledge of my car, etc - I used to get over 40 at the *minimum*. Today's tank yielded 37MPG. :eek:

    I've changed tires twice. I went back to the OEM tires in January this year. I'm right at 72k.
     
  4. seilerts

    seilerts Battery Curmudgeon

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    Other questions:

    How many miles on your car?
    Do you have the yellow "check engine" light on?
    Have you jacked up the car to make sure that each wheel turns freely?
    Have you checked your hybrid battery fan for clogs?
    Have you cleaned the MAF sensor?
     
  5. GrumpyCabbie

    GrumpyCabbie Senior Member

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    North Yorkshire, UK
    Vehicle:
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    Model:
    III
    I'd be inclined to know EXACTLY which make and model of tyre you have and whether they're the same on all wheels. Using non LLR tyres will cause a drop in mpg's.

    Also, as others have said - do all wheels turn freely? At that mileage you could start to be having signs of a failing wheel bearing, especially if you drive through floods or water a lot.

    One weird question for you; Do you own a dog or dogs?
     
  6. Rxmxsh

    Rxmxsh Member

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    Alright! Thinkers.

    1. 72k
    2. No
    3. No
    4. No
    5. No - How do I?
     
  7. Rxmxsh

    Rxmxsh Member

    Joined:
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    Tire - Goodyear Integrity. Went back to OEM. Yes, they are on all 4 wheels.

    Haven't checked the rolling of the wheels. I live in SoCal, and it's great weather 95% of the time. IE - no rain.

    Yes, we have 2. They aren't allowed in the Prius. Not once, lol. We have a Jeep that they utilize. :)
     
  8. F8L

    F8L Protecting Habitat & AG Lands

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    Didn't we have someone with a similar problem that we couldn't flesh out and it turned out to be an injector issue?