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Myth Busters look at open window vs air-conditioning

Discussion in 'Gen 2 Prius Fuel Economy' started by hdrygas, Jun 5, 2005.

  1. hdrygas

    hdrygas New Member

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    I recently saw Myth Busters and they were testing gas milage with air-conditioning vs. open windows. Now the test may not exactly apply to Prius drivers. They used identical Ford Explorers in the test. Put in a known amount of gas and drove at 55 on a track. The air was apparently set at max air because they were complaining it was too cold. The Ford with the open windows did a number of laps after the one on are conked out. Now the Explorer has the drag coefficient of a brick and the air is belt driven on the Engine but it was interesting none the less. I wonder how a test with Prii would have gone other than the obvious running out of gas is a bad idea?
     
  2. Tideland Prius

    Tideland Prius Moderator of the North
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    I remember that episode. I think their verdict was that opening the window was more efficient. HOWEVER, note that they did the test at 45mph which is not even highway speed.
     
  3. hdrygas

    hdrygas New Member

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    I thought it was 55 not highway but near. They complained about holding the car on the track. An Explorer is not exactly an Indy car! They are rerunning it in a half hour I will check it out. Did I mention that I think those guys have the greatest job in the world?
     
  4. rflagg

    rflagg Member

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    55 was the first test, 45 was the second test.

    My problem with their tests - and usually they're quite good at testing all possibilities - is that speed is an important factor. If say, they tested two cars at 90 mph, one with windows down, the other with the a/c, I'd bet good money there'd be quite an advantage for the a/c car.

    However, of course, we all know this doesn't apply to the Prius since we know the windows down are more efficient up until about 45mph or so.

    -m.
     
  5. jayman

    jayman Senior Member

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    I thought it was an Expedition?

    It was interesting how they used a dealer scantool to see how much fuel they were using, and even driving gently those things only got around 12 MPG, A/C or no A/C.

    Jamie and Adam then theorized the scantool was for some reason a poor method to determine actual fuel consumption, so they did the measured amount of gasoline and drove until the things quit.

    I agree, they have the best job in the world. Though I wonder if Adam and Jamie don't get on each others nerves? Usually if you combine a serious introverted guy (Jamie) with a comic extrovert (Adam) the sparks tend to fly.

    Some of my more favorite comments from the show:

    "KABOOM!"

    "Am I missing an eyebrow ... ???"

    Remember the ducks?

    "Quack damn you!"

    My absolute favorite, where Adam had to shave his entire body and was covered in gold paint. The part where they had the paramedic Sanjay do a rectal temperature probe:

    "Oh Sanjay Sanjay .... will you still respect me in the morning?"
     
  6. V8Cobrakid

    V8Cobrakid Green Handyman

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    well.. our A/C isn't belt driven. it doesn not rob HP which is worse than robbing electricity from our prius.

    I said this in another post. With my AC on 72 degrees, i'm able to achieve 55 to 60 mpg on the highway. i can not achieve those numbers with my windows down.

    The whole scenario switches under 45 or so. I consider 45 a city speed. I turn the A/C off and crack my windows.
     
  7. skruse

    skruse Senior Member

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    At less than 45 mph: I set the AC at the coldest temperature. Select the maximum number of outlets (dash front and sides and floor). Turn the AC OFF. Open the two rear windows 10 to 15 cm. This results in good air flow through and reasonable cooling of the interior - even on warm days. No affect on fuel economy.
     
  8. mikepaul

    mikepaul Senior Member

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    When the Today show was covering their 3-car convoy to show gas efficiency a week or so ago, they used the A/C-is-better-than-open-windows line.

    Not sure this scenario will make them believe they were wrong...
     
  9. V8Cobrakid

    V8Cobrakid Green Handyman

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    <div class='quotetop'>QUOTE(skruse\";p=\"95847)</div>
    i was wondering how to get better flow. i achieved it one day. i know the AC gets air pulled through it. bad windows work best though? hmm
     
  10. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    i get good flow by cracking the rt front and left rear
     
  11. hdrygas

    hdrygas New Member

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    Being a frustrated scientist I love to collect data. We should contrive to run our own experiment. The hardest part will be doing a test that is doable given the m.p.g. The Myth busters used 5 gallons of gas. At that rate we could be at it for quite a while.
     
  12. V8Cobrakid

    V8Cobrakid Green Handyman

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    the bad thing about the mythbusters is.. unless they changed out the gas tank, there could be fuel still strapped in their. was it a flat track? was it a circular racing track? i think it might be easier to with out bladders. all depends on the exact shape i guess.
     
  13. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    i saw the the show and i didnt think it was a thorough test also i also think that the Prius would be more affected by the windows being open because its Cd is so low.

    the test vehicles used on the show had such sucky Cd ratings that having a window open does affect it as much

    its like the hummer's gas mileage. if you lose 10%, that is a mile per gallon... not really noticeable but lose 10% or 5 mpg in a Prius and that you will notice right away
     
  14. jayman

    jayman Senior Member

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    <div class='quotetop'>QUOTE(V8Cobrakid\";p=\"96268)</div>
    It was actually a highly banked roundy-round track. Jamie (The serious and safe person) had legitimate concerns about how the Expedition tires would handle "normal" highway speeds around that sort of track.

    Due to the extreme steering involved in the tight corners, you could hear tire squeal, and after only 10 laps there was pronounced tire edge wear. They were worried that if a tire popped around a corner they might flip the Expedition.

    It goes without saying an Expedition doesn't cut it at a race track. FYI it was their Episode 22:

    http://dsc.discovery.com/fansites/mythbust...episode_02.html
     
  15. Tideland Prius

    Tideland Prius Moderator of the North
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    I really thought it was the Explorer. Hmm...
     
  16. DanMan32

    DanMan32 Senior Member

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    I hope they had both vehicles taking on the same path at distances far enough so they aren't drafting. If one was on the inside track, it will run longer. One could of course correct for this by switching roles and testing again.
     
  17. bruceha_2000

    bruceha_2000 Senior Member

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    <div class='quotetop'>QUOTE(hdrygas\";p=\"96266)</div>
    Could invalidate the test as well when we have to stop for a pee break! :D
     
  18. jayman

    jayman Senior Member

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    <div class='quotetop'>QUOTE(bruceha_2000\";p=\"96354)</div>
    Bruce:

    Actually, on the show Adam solved that little problem by using an empty container. Imagine that some women still think that men aren't creative!

    Not as silly as it sounds. The "piddle pack" has been used by the U.S. Air Force for a long time now, and if you fly something like a Cessna 172 you can get a "Li'l Jonny" from Sporty's Pilot Shop.

    Jay
     
  19. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    there was a story on the local news about "trucker bombs" (mostly gallon milk containers filled with pee) littering the highway. one survey found 14,000 of them between Everett and Tacoma one Saturday afternoon.

    these things are considered biological hazards
     
  20. jayman

    jayman Senior Member

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    Dave:

    YUCK!

    Jay