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Another where'd my MPG go thread...

Discussion in 'Gen 3 Prius Fuel Economy' started by billnchristy, May 12, 2011.

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  1. billnchristy

    billnchristy Active Member

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    My 2010 was purchased in July of 2009 and we are at just under 40k right now.

    About 800mi or so ago I had to replace the Yokohama Avid S33s that were on the car. I bought Michelin Primacy MXV4s because the Energy Savers were not in stock and my babies were bald.

    Prior to replacing the tires I had 2 tanks over 50mpg and was actually averaging around 55, this is gal/miles calculations not display.

    My commute is short and I understand I take a hit in the morning, its an 8mi hike with hills and traffic and generally sucks BUT...worst MPG in winter was around 44mpg.

    I have now had 2 tanks (one short fill) of 43mpg or less.

    When the tires were changed I took the wheel covers off, so tires and wheels were the only changes.

    It is very hard to even hit 50mpg on the highway anymore.

    I am taking it in for an oil change today, a little premature but we did note that in the past right near the 5k mark the MPGs suffered so I am hoping this and new tires are combining for bad mileage.

    I expected a 1-2mpg hit from new tires but not 7+

    Should I talk to the dealer or continue to try to suss this out?
     
    #1 billnchristy, May 12, 2011
  2. billnchristy

    billnchristy Active Member

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    A little more info:

    Non-trip MPG usually around 48mpg calculated
    Winter MPG usually around 44-45mpg calculated
     
    #2 billnchristy, May 12, 2011
  3. kenoarto

    kenoarto Senior Member

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    Check your alignment?
     
    #3 kenoarto, May 12, 2011
  4. billnchristy

    billnchristy Active Member

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    Can you have alignment issues even if the car tracks straight if you let go of the wheel?
     
    #4 billnchristy, May 12, 2011
  5. mikewithaprius

    mikewithaprius New Member

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    Hey Bill, it took me a minute, but do you mean that around 5k mile intervals (not 5k on the odometer) your mileage drops?

    I'm guessing you've checked this stuff, so excuse me if it's too basic...but have you checked for any differences in tire pressure? Less likely, but oil level? Are air filters nice and clean?
     
    #5 mikewithaprius, May 12, 2011
  6. wstevensiv

    wstevensiv New Member

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    and were sure its not the tires? i know they are lrr, but the bald yoko's might have been giving a good mpg because of how bald they were.

    check all that stuff mentioned and then pump up the pressure in those michelins...
     
    #6 wstevensiv, May 12, 2011
  7. sipnfuel

    sipnfuel New Member

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    Did they rebalance your tires?
     
    #7 sipnfuel, May 12, 2011
  8. billnchristy

    billnchristy Active Member

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    I expected, like others have posted, a 1-2mpg hit over normal.

    My normal was 48 but I am seeing 43 or worse (Current MFD is 46.8 which is around 43-44).

    I checked pressures last night and they were 40/35 or so and bumped to 42/40.

    I agree the bald yokos were giving me that 48 to 50+ boost its just the 48 to 43 that is confounding me.
     
    #8 billnchristy, May 12, 2011
  9. billnchristy

    billnchristy Active Member

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    They were supposed to.

    I have had a trip to Greenville and one to whitesburg (130 and 75 mi respectively) and have not had any shaking or anything to show them not being right....have even been up to 90mph avoiding an idiot on I-85...no shimmy or shake.
     
    #9 billnchristy, May 12, 2011
  10. sipnfuel

    sipnfuel New Member

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    The difference in tire size, and the new vs old tires can account for almost 3% MPG loss.

    Factoring in your shorter commute can shave another few MPG.

    Also since these tires are not LRR and you are looking at a few more MPG.

    Taking wheel covers off, maybe 0.5 - 1 mpg hit?

    I would note your MPGs on your next much longer road trip to eliminate as many variables as possible.
     
    #10 sipnfuel, May 12, 2011
  11. billnchristy

    billnchristy Active Member

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    If not LRR why does Michelin say they are Green X tires?

    Same tire size 195/65/15

    Same commute as when I was getting 48
     
    #11 billnchristy, May 12, 2011
  12. sipnfuel

    sipnfuel New Member

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    ^ My mistake if they are. I searched TireRack for LRR and they weren't on the list.
     
    #12 sipnfuel, May 12, 2011
  13. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    pump em up to 45 PSI. all you can do at this point. insure good alignment, but its the tires.
     
    #13 DaveinOlyWA, May 12, 2011
  14. billnchristy

    billnchristy Active Member

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    It's odd...Tirerack shows 2 sizes as LRR and Michelin shows 2 sizes are not.

    I will call Michelin and if they say they aren't then I am going to give them hell since I went for them based on that and lack of availability for the Energy Savers.

    At this point they are "only" costing me $177 a year in gas so its not worth the 600 hit to change again.

    Maybe I will try the covers back on again too. Does anyone know if you can leave the center caps on and re-fit the hubcaps?

    I know I shouldn't have changed so many variables at once, very unscientific of me but I didn't expect a hit that bad.
     
    #14 billnchristy, May 12, 2011
  15. richard schumacher

    richard schumacher shortbus driver

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    The wheel covers don't make a gnat's nice person of difference. It's the tires. Inflate the fronts to the maximum shown on the sidewalls and the rears to 2 PSI less, and see what happens over a dozen tanks.
     
    #15 richard schumacher, May 12, 2011
  16. jdcollins5

    jdcollins5 Senior Member

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    Others on here have noted that they have taken a 1-2 mpg hit when first changing out to new tires. Once the tires had a little wear they were able to regain their lost mpg.
     
    #16 jdcollins5, May 12, 2011
  17. billnchristy

    billnchristy Active Member

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    I didn't think so either but at this point my Fiesta isn't performing much worse so I was kinda getting desperate.

    I'll chill and see what happens. :)
     
    #17 billnchristy, May 12, 2011
  18. mikewithaprius

    mikewithaprius New Member

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    Make sure you don't let the Fiesta beat your Prius on one of its tanks. I don't quite know what would happen, but I imagine there would be some sort of dire consequences for the entire world.
     
    #18 mikewithaprius, May 12, 2011
  19. billnchristy

    billnchristy Active Member

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    There are a couple guys on Fiesta Faction that have had 43 and 51 mpg tanks so there are some crazy non-hybrid hypermilers out there doing it already.
     
    #19 billnchristy, May 12, 2011
  20. mikewithaprius

    mikewithaprius New Member

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    haha I know, was just kidding. ECOManiac is a Fuelly friend. 52 mpg is awesome for an ICE! He does have a dream commute...told me he drives 45-50 mph for 75 miles a day with few lights and avoids local trips. Great setup.
     
    #20 mikewithaprius, May 12, 2011
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