mudguards/flaps affecting mpg?

Discussion in 'Gen 2 Prius Fuel Economy' started by arvind, Jul 16, 2009.

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  1. arvind

    arvind ape

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    mud guards killing MPG?

    Hi

    Has anyone experienced this? I put mudguards on my prius and watched my MPG drop by 3-4. I used to average about 47-48 in my car and after installing them, I average 42-44. I had my car service at Toyota Magnussens in Palo ALto and noticed the drop off afterwards. Is this normal or out of the ordinary. Im tempted to take them off but I believe they glued them as well so it might be messy.
    Any ideas on this one?

    THanks:confused:
     
    #1 arvind, Jul 16, 2009
  2. arvind

    arvind ape

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    Hi

    Has anyone experienced this? I put mudguards on my prius and watched my MPG drop by 3-4. I used to average about 47-48 in my car and after installing them, I average 42-44. I had my car service at Toyota Magnussens in Palo ALto and noticed the drop off afterwards. Is this normal or out of the ordinary. Im tempted to take them off but I believe they glued them as well so it might be messy.
    Any ideas on this one?

    THanks
     
    #2 arvind, Jul 16, 2009
  3. yardman 49

    yardman 49 Active Member

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    Did you check your tire pressures? Maybe they did you a "favor" and reset them back to OEM specs??
     
    #3 yardman 49, Jul 16, 2009
  4. ksstathead

    ksstathead Active Member

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    Re: mud guards killing MPG?

    What if anything besides the flaps was done in this service?

    If fluids or alignment, that could cause problems, for example.

    You figure it will make your cd worse, and I suppose this difference could result, although it seems like a lot. If they REDUCED drag, toyota would have put them on to begin with.

    Suggest you do a coast down in N to a stop on a specific flat stretch. Then if you do get them removed (I'd guess they can heat the glue free), repeat in the same conditions. If you don't get measurably further, then something else was in play.

    Real question is how to rule out other factors before removing. Ideas, anyone?
     
    #4 ksstathead, Jul 16, 2009
  5. ksstathead

    ksstathead Active Member

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    There you go yard, with the obvious easy answer...
     
    #5 ksstathead, Jul 16, 2009
  6. yardman 49

    yardman 49 Active Member

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    Re: mud guards killing MPG?

    I wonder if the dealership did you a "favor" and returned your tires to "factory" pressure specifications??
     
    #6 yardman 49, Jul 16, 2009
  7. LRKingII

    LRKingII New Member

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    Re: mud guards killing MPG?

    This would be my bet if you had them pumped up higher the factory specs
     
    #7 LRKingII, Jul 16, 2009
  8. LRKingII

    LRKingII New Member

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    Why are you posting this in 2 different threads?
     
    #8 LRKingII, Jul 16, 2009
    1 person likes this.
  9. arvind

    arvind ape

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    wasnt sure what section it should be in. sorry
     
    #9 arvind, Jul 16, 2009
  10. arvind

    arvind ape

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    i thought the same and I reinflated my tires back to 52 in front like before. still no dice....
     
    #10 arvind, Jul 16, 2009
  11. arvind

    arvind ape

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    Re: mud guards killing MPG?

    ive tried to reinflate and still no dice. In fact ive noticed the dropoff from 44 to 42.5. its been pretty steady and im guessing it must be the mudguards. i put them on for looks mostly with the side moldings. car looks great but i didnt expect the dropoff... ill take the MPGs over the mudflaps any day. Has anyone else experienced this?
     
    #11 arvind, Jul 16, 2009
  12. arvind

    arvind ape

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    Re: mud guards killing MPG?

    I had my 60k service done and had the flaps put on with side moldings... Im pissed that my car is getting worse mpg's. I dont drive wild or anything...
     
    #12 arvind, Jul 16, 2009
  13. LRKingII

    LRKingII New Member

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    Re: mud guards killing MPG?

    Have you checked the engine oil level?
     
    #13 LRKingII, Jul 16, 2009
  14. patsparks

    patsparks An Aussie perspective

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    Re: mud guards killing MPG?

    Funny thing is, I got my best tank just after I put the mudflaps on my Prius.
    I normally get about 4.3L/100km but after fitting mudflaps I got a 4.0L/100km tank. Since my tanks around town have aool been in the 4.3 ballpark.
    Did you also have the tyres rotated? That might affect fuel consumption a little for a while.
    Check oil, tyres, AC use, windy weather, change of commute, etc.
     
    #14 patsparks, Jul 16, 2009
  15. arvind

    arvind ape

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    Re: mud guards killing MPG?

    Havent checked any levels yet. Just had it serviced about 2 months ago. I have a short commute too. Im hesitent to take off the flaps just to check if this is the issue.... I really hope it isnt and its something else... minor.
     
    #15 arvind, Jul 16, 2009
  16. blueumbrella

    blueumbrella Member of Prius Regeneration

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    Re: mud guards killing MPG?

    arvind- I would hold off removing the mud flaps until you have ruled out all other possible causes. It imagine a number of folks on this forum have installed these same mud flaps and should be able to share their experiences. It does not sound right to me.
     
    #16 blueumbrella, Jul 16, 2009
  17. zonie911

    zonie911 Member

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    Re: mud guards killing MPG?

    I've thought about having flaps put on my car, because I know they will look really good, but I've been afraid of affecting the mpg's.You read about hypermilers and some of them even take off their side mirrors, etc., so it makes sense that there would be a certain amount of drag with flaps.
     
    #17 zonie911, Jul 16, 2009
  18. hschuck

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    Re: mud guards killing MPG?

    Not only do they look good, but, they are very functional.

    I noticed no change in fuel efficiency when I installed mine.
     
    #18 hschuck, Jul 16, 2009
  19. accordingly

    accordingly Member

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    Re: mud guards killing MPG?

    Just take them off and see if it goes back up. Then repeat to make sure. Then do it again :).
     
    #19 accordingly, Jul 16, 2009
  20. topkick

    topkick Member

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    Re: mud guards killing MPG?

    I put mud guards on my 2007 Prius and really wished they were available for the 2010 and will buy them as soon as I can.

    I never noticed any hit to the MPG but they sure helped keep the junk off the lower panels when the streets were wet or on snow and ice.
     
    #20 topkick, Jul 16, 2009
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