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Better at high elevations?

Discussion in 'Gen 2 Prius Fuel Economy' started by icecreamchick, Aug 6, 2005.

  1. icecreamchick

    icecreamchick New Member

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    Greetings!

    I live in central Missouri (elevation 850 ft., m/l) and typically achieve about 44 mpg at interstate-level (75mph) speeds. Less than most of you are getting, but I'm pretty pleased.

    I just returned from a trip to Santa Fe, Taos, and Chama, NM (elevation 7000-9000 ft., m/l) and consistently achieved mileage around 54 mpg at that elevation, which is about a 25% improvement.

    Can anyone explain why this would be?

    I know that the air density decreases by about 10% for every mile or so of elevation, which is why there are so many home runs hit at the Colorado Rockies' stadium. So that should play a factor, but is the thinner air the only reason for the big jump? Is there something else at work?

    Thanks in advance for your musings on the subject.
     
    #1 icecreamchick, Aug 6, 2005
  2. efusco

    efusco Moderator Emeritus
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    Without a bit more info it's hard to say. Did your average speed decrease from the 75 mph you're used to? Dropping even to 65mph could, alone, account for your improved mileage. Throw into the mix that you probably drove for longer times, with fewer stops and slow downs and now the thinner air and heck yea, there's lots of reasons your mileage improved.

    I suspect you could do better with your central MO mileage too using some technique and dropping your speed just a bit.
     
    #2 efusco, Aug 7, 2005
  3. icecreamchick

    icecreamchick New Member

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    Evan--
    I know that dropping my speed a little will greatly improve mileage, but as a fellow Missourian, you also know that driving less than 80 on I-70 will surely get you killed! :wink:

    But back to the mountain question--the bulk of the driving I did was at around 75 mph on interstate-quality roads. So the elevation or the terrain are the only variables I can come up with.

    I suppose that despite getting something pitiful like 15mpg while driving *up* the mountain, this crummy mileage could be more than counteracted by getting >100mpg going *down* the mountain and that could account for the overall increase. Does that logic fly with anyone?

    Thanks for your help.
     
    #3 icecreamchick, Aug 10, 2005
  4. tomdeimos

    tomdeimos New Member

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    From Wayne's Palm program your elevation change should account for about 10 mpg of your mpg differences. This matches pretty good with what you got.
     
    #4 tomdeimos, Aug 10, 2005
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