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AC on or open up windows?

Discussion in 'Gen 2 Prius Fuel Economy' started by dennisd, Oct 13, 2004.

  1. dennisd

    dennisd New Member

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    I have been wondering if it is more economical to drive with the windows open or with the windows closed and the AC running. I know the Cd is very low on the car and open windows will cause wind turbulence in the car. I am sure the temp. you set the AC at and the speed of the fan will also impact gas mileage. There are many factors involved (speed, temp, etc.) but, in general, what do you all think?
     
  2. jamarimutt

    jamarimutt New Member

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    If it is hot, I turn on the air conditioner. If it is nice outside, I lower the windows; however, if it's windy and noisy, I roll up the windows and turn on the air conditioner. In other words, comfort, not mpgs, is the main criterion for using or not the air conditioner.

    I am not falling for the trick of compromising the pleasure of driving for a couple of mpgs.
     
  3. prius04

    prius04 New Member

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    I've been hearing the arguments on this for the last 40 years. I still don't know what the anwer to this question is, though I suspect the AC is more economical than open windows, but I'm very curious what responses you get on this. And I suspect this is even more true of the Prius.

    I'll be paying attention.
     
  4. V8Cobrakid

    V8Cobrakid Green Handyman

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    I was trying this out today. It's 90 Degress outside.. 91 in certain spots. Not an ideal time to test this.. but i did. With A/C on.. set to 78/80.. i achieve around 40-50 on my mpg bar graph... when i had the widows down, i was able to achieve 75+ because the battery stayed fuller.. i was able to cruise in "no arrows" more often. If it was cooler outside (70's) then i would keep the windows down. In the winder, i plan on keeping the windows down. It doesn't get very cold in CA. This is why i like driving at night.

    If you're doing below freeway speeds, the windows down don't seem to be a problem. But 60 and over, you might as well turn the AC on.
     
  5. rflagg

    rflagg Member

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    I believe the reported speed where windows are less efficient than a/c in the 2004 Prius is 46mph. Try a search for a/c efficency, but spell it correctly unlike myself. :) I know it's in the range of the 40mph's.

    -m.
     
  6. DonDNH

    DonDNH Senior Member

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    I have found that during my commute at 45 - 60 MPH that the A/C set to auto and the temp set comfortably is best. Overall milage for the summer has been 54 - 55 MPG.

    With the temps dropping, so is the mileage.
     
  7. DaveG

    DaveG Member

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    <div class='quotetop'>QUOTE(jamarimutt\";p=\"45046)</div>
    Well said! I'm exactly the same way. I'll try and use the Prius to get the best milage possible, so long as it doesn't compromise my driving comfort and enjoyment.

    Dave.
     
  8. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    i ran the air conditioner all summer and my mileage was still pretty good. now that i've had the chance to go without the air for extended periods, it seems like my mileage has improved only 2-3 mpg.

    on the window thing. i was told that only opening one window has a small effect on the Cd. opening two windows more than quadruples the drag on the car.

    dont know how true that is, but do know its a lot windier with two windows open than with only one.

    but all in all, it boils down to comfort. for me, it doesnt have to be very hot before open windows stop doing it for me. with a thermostatically controlled air, you can control the hit on your mileage if you feel the need.