Fuel economy dropping.

Discussion in 'Gen 2 Prius Fuel Economy' started by Jghake, Feb 21, 2013.

  1. Jghake

    Jghake Junior Member

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    I just bought this 09 pkg 6 a few weeks ago. I started out with 43mpg and it has been declining ever since. Our driving style has been improving per another Prius owner friend. He tells me we are driving it correctly. Our daily routes haven't changed but we are driving it 82 miles round trip 4 days a week and 42 another 2 days just for commuting.

    The only thing that has changed since we bought it is that I bumped the tire pressure up to 40psi about a week ago and I had the steering and hybrid pump recall work done yesterday at my local Toyota dealer.

    Tires are almost new Pirelli four seasons in the stock size. 94k miles on the car.

    I bought this car solely for its MPG. Does anyone have any ideas?
     
  2. jdenenberg

    jdenenberg EE Professor

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    The dealer may have dropped the PSI back down to 35/33. Check it.

    JeffD
     
  3. Jghake

    Jghake Junior Member

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    I will do that when I get home. The odd part is we were getting 43 before I increased the tire pressure. Each tank since we bought it has been progressively lower MPG.
     
  4. jdenenberg

    jdenenberg EE Professor

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    MPG is sensitive to weather (cold, wind and wet each lower MPG). Short trips also lower MPG as both the engine & catalytic must warm up before the HSD helps.

    You also have a bladder in the fuel tank that makes fill ups inconsistent, especially in cold weather.

    JeffD
     
  5. Jghake

    Jghake Junior Member

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    Ok. We have been as careful as we can lately and I don't think the weather had been much colder than the past few weeks. The MPG is at 39 right now which is concerning me.
     
  6. bisco

    bisco cookie crumbler

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    when you say it's 39, how are you tracking it?
     
  7. Jghake

    Jghake Junior Member

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  8. uart

    uart Senior Member

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    Hi Jghake. Have you been resetting the MPG data on the multifunction display when you fill up? If not then the "started out at 43MPG" may have been the long term average from the previous owner.
     
  9. Jghake

    Jghake Junior Member

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    I reset it every time I fill it up. The 43 was our first tank after the reset.
     
  10. Jghake

    Jghake Junior Member

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    Do I need to do "normal car things" to this Prius?

    New air filter, new spark plugs, replace belts, etc. to keep the MPG's up?
     
  11. uart

    uart Senior Member

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    I hadn't seen your previous reply or the "fuelly" data before I posted that last reply. Looking at the fuelly data it looks exactly like it's moving from a previous average of 43 to a new average of about 39 to 40. I think that it's MPG calculation are just adjusting to a new driver/ new driving style.

    When I first got my s/h prius, it seemed to take a while to "adjust" to my driving style before it's reported MPG really became accurate. You may find that it settles down and then gradually improves over time. You'll probably also get more familiar with the subtleties driving a prius for best mpg.
     
  12. bisco

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    could be the weather, your driving habits/route, someone else's habits, bad 12 volt battery, when did you put new shoes on her? what were the mpg's before the recall work? maybe reduce the tire pressure and see what happens.
     
  13. Jghake

    Jghake Junior Member

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    The tires were on there when we bought the car a few weeks ago. The tread is in really good shape so my guess is they aren't very old.

    The recall work was done yesterday so I haven't had a full up since hit it seems to keep declining.

    The 12v batter was replaced by Toyota in November of las year. I am able to see all of the service for the car since it was new because the previous owners only serviced it at the dealer. That is definitely nice to have.
     
  14. bisco

    bisco cookie crumbler

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    no and yes. they don't need random maintenance, but will affect mpg's. air filter every 30,000 or sooner if you're in dusty conditions. i would check it, a dirty air filter will reduce mpg's. it's easy and cheap to replace. plugs at 120,000, belt around 100,000. but doesn't affect mpg's, regular oil and filter every 5,000, make sure it's not above the 'full' line. rotate tires every 5,000, won't affect mpg's. cabin filter every 15,000, won't affect mpg's. car doesn't need much maintenance.
     
  15. dorunron

    dorunron Senior Member

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    What settings do you have the climate control set on? Also are you using the AUTO setting? If it is in Auto, the A/C compressor is running which will tend to contribute to low MPG.
     
  16. Jghake

    Jghake Junior Member

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    We have it set to auto until the cabin is comfortable then we usually turn it off. The mileage started to go up. The tank is now empty and the dash says 43.4. I will fill up and put the data into Fuelly to see what it does.
     
  17. dorunron

    dorunron Senior Member

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    If you are running auto, you can push the A/C button in the climate control. The little line underneath should go off. That will turn off the compressor. Try keeping the compressor off during the winter. Less pull on the traction battery which should help with the MPG. If you want to turn the compressor back on, either push the button again (A/C) or push Auto on the MFD. Good luck to you.
     
  18. Justdidit

    Justdidit LVNPZEV

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    Do you always get gas at the same station? I found I get different MPG depending on where I buy my Gas. Cheaper gas (mom&pop stations) = bad MPG....Stations more well known with fuel additives = better MPG. I think a lot of it can also be contributed to the quality of Gas.
     
  19. Jghake

    Jghake Junior Member

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    I have consistently tracked this with my Explorer and found that it didn't make a difference with the mileage. The variance was very small.

    We haven't owned the Prius long enough for us to determine this. Usually we buy Shell, Safeway, Fred Meyer, or Arco gas.

    This last tank ended up being the highest MPG tank since we bought it. Click on the car in my signature to see details. I'm not sure why it started registering so low.
     
  20. fuzzy1

    fuzzy1 Senior Member

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