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Better mileage questions

Discussion in 'Gen 2 Prius Fuel Economy' started by airman, Feb 18, 2008.

  1. airman

    airman New Member

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    I have noticed that I get about 48 mpg if I really accellerate slowly and coast down hills to regen power. The really interesting thing that confuses me is that I tried driving the Prius in a more spirited way, not caring about the acceleration rate and even having a bit of fun and it gets better mileage.....51-52. Both numbers were recorded on similar temp days. What gives? All mileage were on the same combined city, county roads and same temps. So it seems the more fun it is to drive the better the mileage???:eek:
     
    #1 airman, Feb 18, 2008
  2. Stringmike

    Stringmike New Member

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    I am allowed to drive my wife's Prius occasionally and nearly always worsen the gas mileage, despite practicing gentle (not quite hypermiling) techniques. She commutes about 35 miles a day, mostly on an urban freeway at 65 mph and averages 48 to 49.5. Under my more careful driving, it usually drops a couple of percent to 47 to 48.

    I wouldn't say she's a lead-foot (she reads this forum!), but she's no slouch.

    Mike
     
    #2 Stringmike, Feb 18, 2008
  3. ken1784

    ken1784 SuperMID designer

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    I believe your observation is correct.
    Slow acceleration does not mean hypermiling.
    We used to say do a brisk acceleration for hypermiling.
    The right amount of acceleration causes good results.

    Ken@Japan
     
    #3 ken1784, Feb 18, 2008
  4. qbee42

    qbee42 My other car is a boat

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    Brisk acceleration allows the ICE to run in a more efficient zone. You use more gas, but for a shorter period of time. Ideally you want to accelerate with the ICE running at some sweet spot, but it's impossible to know exactly what that is without more instrumentation. As a general rule, try to accelerate up to speed quickly but without drawing from the HV battery. Obviously, if you are going to have to stop right away, at the next light for example, avoid accelerating any more than necessary.

    Another mileage mistake commonly made by new Prius drivers is trying to maximize the time in electric mode. Driving in electric or EV mode is a mileage killer. There are special cases where it makes sense, but in general, it hurts instead of helps.

    Tom
     
    #4 qbee42, Feb 18, 2008
  5. efusco

    efusco Moderator Emeritus
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    I'll add that coasting down hill to regenerate is also inefficient.
    Given the option you should go down the hill in a glide...no arrows showing at all on your MFD (achive this with very gentle pressure on the accelerator until the arrows disappear).

    Regen is not 100% efficient so you're actually converting your kinetic energy into passive/stored energy then you try to reclaim it later...incuring losses each time. Better to Glide and allow gravity to increase your momentum and then use your momentum at the bottom of the hill to maintain the glide and delay when you need to use gas again. Safety is always the first priority of course.
     
    #5 efusco, Feb 19, 2008
  6. patsparks

    patsparks An Aussie perspective

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    Adding to Evan's words of wisdom, if you allow your speed to drop a little below the desired speed as you crest a hill then allow gravity to add to your speed to a little over but beware you don't speed (too much).

    I think my biggest gains are from looking well ahead and timing traffic to avoid stopping and if I have to stop I do it over the maximum distance. I am always first away and first up to the speed limit at the traffic light drag then back off and gently press the accelerator to maintain speed.

    If you are doing short tripd you have no chance of matching your wife's mileage.
     
    #6 patsparks, Feb 19, 2008
  7. tbirdhs

    tbirdhs Tbirdhs

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    #7 tbirdhs, Feb 20, 2008
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