Sudden drop in Mileage

Discussion in 'Gen 2 Prius Fuel Economy' started by Lou Fezio, Nov 21, 2013.

  1. Lou Fezio

    Lou Fezio Junior Member

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    I have an '05 Prius with 60K miles on it that I bought new. I stay up on the maintenance and drive it gently. I am aware of the car and how it feels so it surprised me to suddenly find my mileage drop 10-20% almost overnight with no obvious symptoms of poor running.

    Most of my driving is around town. In the summer I average 50 mpg and in the winter 47-ish. Suddenly I'm at 41. Where I used to get 60mpg at 60 mph on the highway I now get 50.
    The tires are original and I run them at 35/33 like I always have. Air filter is clean. I haven't done the spark plugs but the engine runs as it always has. I see nothing weird about the state of the drive battery charge. I put a new 12V battery in 2 years ago. I run Mobil 1 5-30 oil as I have since day 1. I put Techron injector cleaner in the gas about every year. I can see nothing wrong with the car. It runs like it always has.

    I'm going to verify that the mileage display is not off by manually calculating the miles/gallon on my next fill-up.

    Otherwise I am stumped. Any ideas?
     
    JMD likes this.
  2. jadziasman

    jadziasman Prius owner emeritus

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    1. Brakes are dragging - does your car decelerate more quickly than usual? I know that would be difficult to judge but if the brakes are not adjusted correctly for some reason that could be the issue.

    2. Wheels are misaligned. Did you hit a curb or a pothole lately. Get the alignment checked. Your car may be traveling down the road without pulling to the left or right but the alignment can still be off enough to affect your fuel economy.

    3. The engine is misfiring - not so much that it will trigger a check engine light but enough to decrease your fuel economy. Bad spark plug, coil, wire, or fuel injector are possible sources.
     
  3. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    Lou, we know very little about you.

    Some Prius owners are having snow, freezing temps, heavy rain, etc. You list no location, so we can't guess (Not strictly true, you must be within 4 light years of Japan for your message to reach us)

    This is your first post, so we are unsure what maintenance you have done in 8 years.

    Weird stuff happening? MPGs dropping? Test The Battery | PriusChat

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

    JMD 2012 Prius 4 Solar Roof

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    12V only last a few years. Worth a look at that.
     
  5. bisco

    bisco cookie crumbler

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    you've gotten 60k out of the original tyres? you must drive slower than me!:p welcome to priuschat!
     
  6. El G

    El G New Member

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    Did you recently have service before this was observed?
     
  7. bisco

    bisco cookie crumbler

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    lou the mystery man.
     
  8. dorunron

    dorunron Senior Member

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    Probably figured out it was the bladder, and the cold temps. Typical for this time of the year ;)
     
  9. bisco

    bisco cookie crumbler

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    i still want to know how he got 60k out of the factory tyres!:p
     
  10. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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  11. dorunron

    dorunron Senior Member

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    probably drives on softer roads :p , 60K is a stretch though imo

    How about it Lou? Care to share some insight on this? Don't know of many who got 60K out of the Integrity's.
     
  12. dorunron

    dorunron Senior Member

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    Yup, that does tend to make a BIG difference, even here in the southwest. FWIW, this winter has been colder than what has been for quite a while.

    Global warming??? Not so sure now :rolleyes:
     
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