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Sudden bad gas mileage 2010 Prius

Discussion in 'Gen 3 Prius Fuel Economy' started by PriusInSanDiego, Sep 11, 2013.

  1. PriusInSanDiego

    PriusInSanDiego New Member

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    Hello!
    I'm live in San Diego and commuted to LA 2-3x a week. The mileage on my car is now at 90k.
    I have had an average of 40 mpg since new, but suddenly it began to drop. We took it to our local Toyota dealer and was told it was most likely a cable that needed to be cleaned. That was $160. It didn't work.

    Today I noticed that my mpg has dropped even more - down to 29mpg! I poked around a little and realized I am actually getting better performance with the ECO setting turned off! I purchased the extended warranty, and plan on bringing it back in to Toyota, but wanted to get your opinions first.

    It has been exceedingly hot here for the last month so it's not the cold weather. I have new tires and checked the pressure Friday. I only use regular gas.

    Any thoughts?

    Thank you!!!
     
    #1 PriusInSanDiego, Sep 11, 2013
  2. bisco

    bisco cookie crumbler

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    welcome to priuschat! 'a cable that needed to be cleaned', i would demand my money back. there are many many possibilities, from bad 12 volt battery to tyres, to battery cooling fan, to throttle body, to hybrid battery and on and on. never heard o f a dirty cable before tho. i would start with a health check on the 12 volt. all the best!(y)
     
    #2 bisco, Sep 11, 2013
  3. PriusInSanDiego

    PriusInSanDiego New Member

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    Thank you for the welcome! I thought it was odd too. Def check the 12v!

    Wanted to add......
    I just looked at the worksheet from the service, and it said we paid for a "throttle body cleaning service" @ $165. My husband said cable... He's not very mechanically inclined. Lol
    The service did nothing and its getting worse.
     
    #3 PriusInSanDiego, Sep 11, 2013
  4. bisco

    bisco cookie crumbler

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    that's unfortunate, but i suppose it may have been worthwhile even so, many here have done it.
     
    #4 bisco, Sep 11, 2013
  5. sisharp

    sisharp Member

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    how's the air filter? has it been changed? you can check this yourself since it's a simple process of undoing the latches pulling the filter out and having a look. Just put it back in the the same direction it was facing.
     
    #5 sisharp, Sep 11, 2013
  6. ksstathead

    ksstathead Active Member

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    Find cwerdna's mpg checklist thread. It is stickied in the fuel economy forum, and completing it will help folks here narrow down what has changed. You mentioned tires, but not which, or when. You are nearing time for new plugs; perhaps a problem there. Bad 12V's have been an issue. If yours is original, then it is about time for it to die.
     
    #6 ksstathead, Sep 11, 2013
  7. retired4999

    retired4999 Prius driver since 2005

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    #7 retired4999, Sep 11, 2013
  8. Former Member 68813

    Former Member 68813 Senior Member

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    Here you go:
    hot weather = more AC use
    new tires = increased rolling resistance, especially if not LRR ones

    And most important part: slow down!
     
    #8 Former Member 68813, Sep 11, 2013
  9. TheEnglishman

    TheEnglishman Member

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    How about the O2 sensors? They can kill gas mileage on ANY car if they're broken.
     
    #9 TheEnglishman, Sep 11, 2013
  10. bwilson4web

    bwilson4web BMW i3 and Model 3

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    You get a "Check Engine" light if more than about 3 minutes.

    Bob Wilson
     
    #10 bwilson4web, Sep 11, 2013
  11. spiderman

    spiderman wretched

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    parking brake? :)

    have you had it regularly serviced?
     
    #11 spiderman, Sep 11, 2013
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