[mo_focus]

I'm just watching Mythbusters and that was the test, AC ON or windows down is better for fuel economy.
2 tests performed.
test 1:
Drive the SUV at 55MPH windows up ac on at 11.7MPG
Drive the SUV at 55mph windows down got 11.3MPG

test 2:
drive two identical SUVs with the exact same pay load and exact amount of fuel. 5gallons. Drive at 45MPH
SUV with AC on run out of fuel faster. the SUV with windows down drove 15 more miles before it ran out of gas.

weird eh?

so what could of caused the two different results. I was always told to drive with windows up/AC on to save gas.


Thanks Mo

[meford4u]

That show aired last year. Watch more tv and be a lazier bastard

[NOS2Go4Me]

Well, I too read that the increased drag of windows down (all available, mind you) is actually worse than having the AC on.

I would have played with that theory some more this summer myself, but near the end the stupid gas prices curtailed my "benchmark" run to my in-laws in Garson and back again. I like these trips as I tend to get pizza for supper more often than not :P

Seriously... I know my gas mileage isn't much better than in the winter when I have all the windows down as we're cruising down the Trans Can. I'd test with the AC too... but the damn SPI has no balls whatsoever in that scenario. There's just too many hills between NB and Suds to chance not passing something.

[crazikev]

in test 1 was the AC on for both the tests? or just the first run?

Well, i think its all about how fast you are going. AC is going to affect your mileage lineary, same drain going whatever speed. While with your windows it will affect it exponentially. The faster your going to go, the more drag your going to get with the windows down. By the time you reach highway speed, your windows are gonna start hurting more than the AC.

Now i think i have found a solution to this, but i didn't test it out, theoretically it should work, but probably has the same amount of drag.
while driving fast, put both passenger side windows down about an inch or 2 in your focus(sedan). The air will come in, probably around the back right of the car, create a vortex, and leave the front passenger side window, works really good (for the driver). I would might even say it works better than having all the windows down.
Now theoretically, there should be less drag cause 2 windows are only open an inch or 2 instead of wide open. But since the same amount of air coming in and circulating around is about the same, it probably has the same amount of drag.

Also the temperature would also play a roll in this equation. the hotter it is, the less the windows are going to effect the milage when they are down because the air would be less dense so their would be less drag, but would the AC take up more engine power because its not producing as much power with the warmer air?

Someone should make a way too, super heat the outside surface of the car so that the air when it hits it is so thin it barel creates any drag at all. Forget slicing through the air. Slice the air up before you get to it

[2001 ZTS]

mo_focus,Nov 7 2005, 09:02 PM Wrote:so what could of caused the two different results. [right][snapback]154324[/snapback][/right]

About 10mph based on your own post.

Plus because SUV's have the aerodymics of cinder blocks whether the windows are up or down makes no difference at higher speeds.

[darkpuppet]

2001 ZTS,Nov 7 2005, 10:55 PM Wrote:

mo_focus,Nov 7 2005, 09:02 PM Wrote:so what could of caused the two different results. [right][snapback]154324[/snapback][/right]

About 10mph based on your own post.

Plus because SUV's have the aerodymics of cinder blocks whether the windows are up or down makes no difference at higher speeds.
[right][snapback]154348[/snapback][/right]

exactly what I was thinking.

it wasn't a good test taking SUVs out on the track, not to mention that they couldn't guarantee that the tanks had the exact same amount of gas in them right at the start, and that both vehicles were in the exact same state of repair.

For all we know the SUV that got the best mileage with the AC on was the one used in the second test with the windows down.

mythbusters isn't exactly the objectively scientific show it's made out to be.

[Euro Ford Fan]

So how did they control the test? Did they weigh the fuel that was in the tank before it was empty to be sure that both were exactly the same? Did the 2nd SUV follow the first getting the advantage of a draft?

Did they use cruise control or was the driver in control all the time?

I didn't see the show... just wondering.

[Frost__2001]

crazikev,Nov 7 2005, 10:44 PM Wrote:in test 1 was the AC on for both the tests? or just the first run?

Well, i think its all about how fast you are going. AC is going to affect your mileage lineary, same drain going whatever speed.  While with your windows it will affect it exponentially.  The faster your going to go, the more drag your going to get with the windows down.  By the time you reach highway speed, your windows are gonna start hurting more than the AC. 

Now i think i have found a solution to this, but i didn't test it out,  theoretically it should work, but probably has the same amount of drag.
while driving fast, put both passenger side windows down about an inch or 2 in your focus(sedan).  The air will come in, probably around the back right of the car, create a vortex, and leave the front passenger side window, works really good (for the driver).  I would might even say it works better than having all the windows down. 
Now theoretically, there should be less drag cause 2 windows are only open an inch or 2 instead of wide open.  But since the same amount of air coming in and circulating around is about the same, it probably has the same amount of drag.

Also the temperature would also play a roll in this equation.  the hotter it is, the less the windows are going to effect the milage when they are down because the air would be less dense  so their would be less drag, but would the AC take up more engine power because its not producing as much power with the warmer air?

Someone should make a way too, super heat the outside surface of the car so that the air when it hits it is so thin it barel creates any drag at all.  Forget slicing through the air.  Slice the air up before you get to it
[right][snapback]154341[/snapback][/right]

Yes you could do that Kev, but in some people's case they could just open their power sunroofs / moon roofs lol.....

But really I saw this before, and they touched on this in consumers reports on CFTO, and they said if you want your a/c on have it on, on the highways only, and windows down when driving round the city. I already have been doing this since I love having the breaze when in town with the windows down, and I mainly use the moon roof on vent when on the highway, without the a/c but If there is more then me in the car I have the a/c on in highway driving only. It works and you do save a bit on the gas milage.