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better MPG in ambient temps of low 60's vs low 70's (F)

Discussion in 'Gen 3 Prius Fuel Economy' started by Former Member 68813, Oct 30, 2015.

  1. Former Member 68813

    Former Member 68813 Senior Member

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    why is it? seems contraintuitive. for the record i get worse MPG in 80's and above (AC) and 50's and below (heating).

    Edit: this is based on city commuting, pulse/glide, garaged overnight. rains excluded (much lower MPG).
     
    #1 Former Member 68813, Oct 30, 2015
    Last edited: Oct 30, 2015
  2. Mendel Leisk

    Mendel Leisk Senior Member

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    The one time you shut off AC? AC imposes a mpg penalty.
     
    #2 Mendel Leisk, Oct 30, 2015
  3. Former Member 68813

    Former Member 68813 Senior Member

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    no, i don't use AC in low 70's.
     
    #3 Former Member 68813, Oct 30, 2015
  4. qdllc

    qdllc Senior Member

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    My first guess is the impact of AC/Heat. Maybe the temperature affects the road surface in a way that reduces drag/rolling resistance?
     
    #4 qdllc, Oct 30, 2015
  5. JimN

    JimN Let the games begin!

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    I've noticed the same thing. There's probably half a dozen factors.
     
    #5 JimN, Oct 30, 2015
  6. Former Member 68813

    Former Member 68813 Senior Member

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    like what? lower battery temp and more battery utilization?
     
    #6 Former Member 68813, Oct 30, 2015
  7. Former Member 68813

    Former Member 68813 Senior Member

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    weird how people don't want to talk about it. is it some sort of a taboo?

    case in point: the last 2 days were cold, daytime temps in high 50's/low 60's and i'm getting the best mpg since getting new tires a year ago, near 60 mpg. up to now, i averaged 55 mpg. now, my car is garaged, so it doesn't get a cold soak overnight, so this may make some difference.
     
    #7 Former Member 68813, Nov 10, 2015
  8. bisco

    bisco cookie crumbler

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    i think because most of us don't see it, we're baffled.
     
    #8 bisco, Nov 10, 2015
  9. Robert Holt

    Robert Holt Senior Member

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    Wish I had systematic data but don't.
    But my impression has been better mpg as temperature increases up until the low 70s where we start using the AC, which clearly negatively impacts efficiency.
    I had assumed lower energy losses due to lower friction, hysteresis, and cold start losses as temperature increases.
    Will pay more attention to see if we recreate your pattern.x
     
    #9 Robert Holt, Nov 10, 2015
    Pale Fox likes this.
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