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Declining Gas Mileage

Discussion in 'Gen 3 Prius Fuel Economy' started by Troy14, Aug 15, 2014.

  1. Troy14

    Troy14 New Member

    Joined:
    Aug 15, 2014
    1
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    Location:
    Pearland, Texas
    Vehicle:
    2010 Prius
    Model:
    Two
    I have 2010 Prius II. My mileage until about 5 months ago was 50-52 mpg. It has in this period declined to the level of about 41-42 mpg. I get regular oil changes, scheduled tune-ups, my tires are inflated to 40psi. I have tires that are about a year old now that are now LRR but, according to literature I've read, this should only make a 1-2 mpg difference at the most. The timing does not coincide well in this case either. My driving habits are the same. I go to the same place for gasoline. Any one have an idea as to what the problem could be? I will be taking it to the dealer to have the hybrid system evaluated before the warrantee expires.

    Thanks,

    Troy14
     
    #1 Troy14, Aug 15, 2014
  2. schmuly

    schmuly Member

    Joined:
    May 5, 2012
    209
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    Location:
    BC
    Vehicle:
    2012 Prius v wagon
    Your brakes may be dragging have you had them checked lately? Are you filling up at the same gas station, as gas quality makes a difference.
    Welcome to the forum......
     
    #2 schmuly, Aug 15, 2014
  3. JimboPalmer

    JimboPalmer Tsar of all the Rushers

    Joined:
    Apr 14, 2009
    12,470
    6,862
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    Location:
    Greenwood MS USA
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    Your 12 volt battery may well be 4 years old, have you had it checked?

    You can use a multimeter in the morning before you drive it for best results.

    Some, but not all, failure modes for the 12 volt battery leave the inverter trying to charge it continuously. This uses a lot of energy that would otherwise be good MPGs.
     
    #3 JimboPalmer, Aug 15, 2014
  4. dorunron

    dorunron Senior Member

    Joined:
    Jul 17, 2011
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    Location:
    Houston, TX
    Vehicle:
    2013 Prius
    Model:
    Three
    Several things come to mind Troy, the tires might have something to do with it. It has been warm this year, though not as hot as previous summers down here in our area so the A/C is probably getting a good work out right now. It is also possible that the traction battery is weakening slightly. The throttle body might need a good cleaning or the MAF being dirty. I would be happy to look at your car for you if you want a local Prius driver to look at it. I previously owned a Gen II and am now driving a Gen III. If you are interested in meeting, I will be happy to come visit with you and see if I can help you figure out what the problem might be. I live on the north side of Houston by Mattress Mac's place of business on 45 north. I would not mind driving out to Pearland if you want to meet up. You can create a "conversation" with me on the subject if you are interested and might be seeking help on a personal level from someone local in the area.

    Best of luck to you and welcome to Prius Chat.

    Ron (dorunron)
     
    #4 dorunron, Aug 16, 2014
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