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MPG degraded over time

Discussion in 'Gen 3 Prius Fuel Economy' started by prius4owner, Oct 8, 2013.

  1. prius4owner

    prius4owner Member

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    Hi All,

    I have 2011 Prius. When it was new it gave me mpg as high as 52.8, but now it is only giving me about 42.5 . Any help will be appreciated. Attached is the picture of the trips. I reset trip B about 9000 miles.

    I perform regular service. Last time when I talked to dealer about this they run some check and told me that everything is fine. But history says that it is not.

    There is no change in my driving pattern nor anything else since I bought this car. Only thing is it is now almost 1 year 8 months old.

    Thanks,
     

    Attached Files:

    #1 prius4owner, Oct 8, 2013
  2. rdgrimes

    rdgrimes Senior Member

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    I'll vote for tires. When's the last time you checked pressure?
     
    #2 rdgrimes, Oct 8, 2013
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  3. prius4owner

    prius4owner Member

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    Hmm good point. I don't check tire pressure myself, but whenever I give it to service I ask them to do so. But if you see the attached picture, it is trending downwards. It is not that suddenly it started giving me low mileage, but over the time the mileage decreased. I havn't changed the tires since i bought the car as it has enough thread.
     
    #3 prius4owner, Oct 8, 2013
  4. fuzzy1

    fuzzy1 Senior Member

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    If you care about MPG and tire life, then tire pressure is not something to be delegated to the service folks. They are too infrequent, and too unreliable and erratic. YOU must monitor the pressure yourself. Select a target pressure range that suits your wants and needs, and re-adjust to that target as seasons and outdoor temperatures change.

    The slow trend downwards would be consistent with the natural slow loss of pressure, especially if your car was delivered with the same high factory pressure (for the Pacific boat ride) as mine, and the service people didn't add anything until is fell below the door placard numbers.

    Tire pressure can't explain all the difference you see, but seasonal differences could account for the rest.
     
    #4 fuzzy1, Oct 8, 2013
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  5. prius4owner

    prius4owner Member

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    Thanks both of you (fuzzy1 and rdgrimes). I will check the tire pressure and adjust it and see if it gives me better mileage.

    I will update this thread.
     
    #5 prius4owner, Oct 8, 2013
  6. rdgrimes

    rdgrimes Senior Member

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    Try it at 40/38 or thereabouts.
     
    #6 rdgrimes, Oct 8, 2013
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  7. bisco

    bisco cookie crumbler

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    how many miles on her? have you ever had to jump start?
     
    #7 bisco, Oct 8, 2013
  8. prius4owner

    prius4owner Member

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    No I never had to do Jump Start. I have used it almost everyday since I bought it. I have 36000 miles on it.
     
    #8 prius4owner, Oct 8, 2013
  9. prius4owner

    prius4owner Member

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    After your advise and this chat, I checked the tire pressure. I increased it to 39/37. The last tank gave me 45.2 MPG. This is great.
    Thanks.
     
    #9 prius4owner, Oct 17, 2013
  10. riceroni87

    riceroni87 Senior Member

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    this reminds me to check mine
     
    #10 riceroni87, Oct 17, 2013
  11. mediahound

    mediahound Active Member

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    Every time I have my car serviced, they actually deflate my tires to 35 psi (my 17" tires have a max PSI of 45).

    So, definitely do not rely on them to do your tire pressure.
     
    #11 mediahound, Oct 17, 2013
  12. szgabor

    szgabor Active Member

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    I tell the service writer what I want have him/her put it on the paper before I sign (same with oil sample request) ...

    Then I actually check before I drive away ... once the young lady came out looked worried and asked what I was doing.. so I said checking the tire rotation and pressure. This is after I once noticed that they did NOT rotate the tire. Funny story !!!
     
    #12 szgabor, Oct 22, 2013
    Empeegee likes this.
  13. mediahound

    mediahound Active Member

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    Yeah, I'll have to start doing that myself. Also, have them write down 'Do Not Wash' since I don't want anyone else washing (read: scratching) my car.

    It's a good idea to carry a pen and if the service advisor doesn't write it down, you write it down yourself. That way, you have it in writing and can call them on it if they do not comply.
     
    #13 mediahound, Oct 22, 2013
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