LOST JEEPS :: View topic - Windows Open VS Air

Don't you guys ever watch Mythbusters?

At highway speeds - AC is more efficient.

In the city - open your windows.

I LOVE THAT SHOW!! You are right BTW. I have learned so much watching that show. My wife ran throught the parking lot into work the other day and told me her clothes got really wet as a result. I laughed and told her shoe should have walked and she would have dryer clothes. I love Mythbusters.

Real highways have hills. Hills demand power. AC eats power directly at the drive belt. Enough said.

Don't you guys ever watch Mythbusters?

At highway speeds - AC is more efficient.

In the city - open your windows.

It's simply a matter of speed.
At lower speeds (below 50 mph) the increase in HP from the air being turned off outweighs the additional drag from the windows being down. Above the ~50 mph mark, the drag from the windows being open outweighs the power loss of the Air Conditioning being turned on.
Just got back from a weekend trip out of town... about 3/4 highway mileage this weekend with the majority of that being on the Interstate cruising with the windows up and the air turned on at the whopping speed of right around 63 mph... results:
388.1 miles on 18.01 gallons (tank filled to the top of the filler each time) = 21.5 mpg. Not Bad... especially for a 3.7L gas engine carrying the family and a fair load of gear aboard.
Luis

I'm a relatively new Liberty owner, and I’ve been reading these boards for some time now. An amazing amount of information is sitting in these boards for a “newbie” like myself.

With the price of fuel around 1.30 CDN a litre I am watching my driving very closely. I have wondered something since I got my new wheels; what is better for better mileage, windows open, or air conditioner on. And does this “formula” change if I’m driving in the city or on the highway.

Author:	rlitchfield [ Sat Sep 10, 2005 4:28 pm ]
Post subject:	Windows Open VS Air
I'm a relatively new Liberty owner, and I’ve been reading these boards for some time now. An amazing amount of information is sitting in these boards for a “newbie” like myself. With the price of fuel around 1.30 CDN a litre I am watching my driving very closely. I have wondered something since I got my new wheels; what is better for better mileage, windows open, or air conditioner on. And does this “formula” change if I’m driving in the city or on the highway.

Author:	Cacher123 [ Sat Sep 10, 2005 5:54 pm ]
Post subject:
In 30+ yrs of driving I can tell u most assuredly that the drag on the engine from the ac drastically reduces mpgs. Next time u accelerate up a ramp cut off ure ac and watch the little extra burst of power u get. Any clutch running off the motor is gonna reduce your horsepower output. Car enthusiasts will tell u the best way to gain horsepower is to remove all items that run off the engine belts.

Author:	rlitchfield [ Sat Sep 10, 2005 8:06 pm ]
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Cacher123, so your telling me it is better to drive with the windows open then with the AC on...interesting...

Author:	m0th [ Sat Sep 10, 2005 8:38 pm ]
Post subject:
Don't you guys ever watch Mythbusters? At highway speeds - AC is more efficient. In the city - open your windows.

Author:	longarm [ Sat Sep 10, 2005 9:25 pm ]
Post subject:
m0th wrote: Don't you guys ever watch Mythbusters? At highway speeds - AC is more efficient. In the city - open your windows. I LOVE THAT SHOW!! You are right BTW. I have learned so much watching that show. My wife ran throught the parking lot into work the other day and told me her clothes got really wet as a result. I laughed and told her shoe should have walked and she would have dryer clothes. I love Mythbusters.

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Author:	Cacher123 [ Sat Sep 10, 2005 9:58 pm ]
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Quote: I LOVE THAT SHOW!! You are right BTW. I have learned so much watching that show. My wife ran throught the parking lot into work the other day and told me her clothes got really wet as a result. I laughed and told her shoe should have walked and she would have dryer clothes. I love Mythbusters. Was it raining at the time? Oh, and I like Buster!

Author:	Guest [ Sun Sep 11, 2005 11:02 am ]
Post subject:
Generally, I drive with the ac on and my drivers window open unless it's like 100 degrees w/ high humidity.

Author:	ltwgs [ Sun Sep 11, 2005 11:40 am ]
Post subject:
as a summer-lovin redneck, I almost never use a/c (even at 100 & 100%). I can't say that my mileage has been affected by it, but note that most new vehicles are designed to drive at highway speeds with the windows up. This implies that the a/c (or vent) would be running. something to consider... grant

Author:	freetolio [ Sun Sep 11, 2005 11:42 am ]
Post subject:	*I have to call bullsht on this one**
Real highways have hills. Hills demand power. AC eats power directly at the drive belt. Enough said.

Author:	rlitchfield [ Sun Sep 11, 2005 4:19 pm ]
Post subject:
Interesting...so from now on...highway is for AC and city will have windows open. Of course, living in Canada, this only applies to part of the year....the other part....windows closed and the heat CRANKED!!

Author:	Guest [ Sun Sep 11, 2005 4:30 pm ]
Post subject:
Your not the only ones!

Author:	Tightwadsjeeper [ Mon Sep 12, 2005 8:48 am ]
Post subject:
It's simply a matter of speed. At lower speeds (below 50 mph) the increase in HP from the air being turned off outweighs the additional drag from the windows being down. Above the ~50 mph mark, the drag from the windows being open outweighs the power loss of the Air Conditioning being turned on. Just got back from a weekend trip out of town... about 3/4 highway mileage this weekend with the majority of that being on the Interstate cruising with the windows up and the air turned on at the whopping speed of right around 63 mph... results: 388.1 miles on 18.01 gallons (tank filled to the top of the filler each time) = 21.5 mpg. Not Bad... especially for a 3.7L gas engine carrying the family and a fair load of gear aboard. Luis

Author:	Eddo [ Mon Sep 12, 2005 9:19 am ]
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http://www.edmunds.com/ownership/drivin ... sonly..4.* Intresting this article say the oposite, but they where only going 65mph and probably not much of a head wind. If the speed was raised to 70mph it might be different. Either way it is worth the comfort.

Author:	WV(0)IIIIIII(0) [ Tue Sep 13, 2005 10:25 am ]
Post subject:	*Re: I have to call bullsht on this one**
freetolio wrote: Real highways have hills. Hills demand power. AC eats power directly at the drive belt. Enough said. Real hi-ways have hills sometimes: not one big hill

Author:	freetolio [ Wed Sep 14, 2005 1:01 am ]
Post subject:	AC vs Windows
http://www.treehugger.com/files/2005/06 ... or_d_1.php The typical mileage gain of "windows down/AC off mode" is a few percent for a sedan but can range as high as 10% for trucks and SUV's (see graphic for SUV example). in the graph 110 kph is around 68 mph, and significantly less gas usage is achieved by using windows instead of AC I tend to believe GM engineers doing SAE tests over the mythbusters.

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Author:	Guyute1210 [ Tue Sep 13, 2005 1:19 pm ]
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m0th wrote: Don't you guys ever watch Mythbusters? At highway speeds - AC is more efficient. In the city - open your windows. Right! what m0th said.

Author:	m0th [ Wed Sep 14, 2005 2:06 am ]
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Personally the reason I run the AC at highway speeds has nothing to do with whether it's more efficient, it's the noise. And mentioning the Mythbusters thing was a joke BTW. From memory, the difference they found was minimal, and they were only testing at one fairly low speed.

Author:	LoganSix [ Fri Sep 16, 2005 2:07 pm ]
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If it's not humid out, I drive with the windows down. I haven't seen much difference. Of course, that's back when I had MTR's on. I'll have to compare the difference with the new road tires I put on. I did build a custom shelf in the back that prevents the air from going down into the trunk cavity. The shelf prevents the helicopter buffetting noise and may help with the drag, but probably not much. I would like to be able to replace the rear quarter windows with minivan style quarter windows to allow for the air to vent out the back.

Author:	Tightwadsjeeper [ Mon Sep 26, 2005 4:57 pm ]
Post subject:
Tightwadsjeeper wrote: It's simply a matter of speed. At lower speeds (below 50 mph) the increase in HP from the air being turned off outweighs the additional drag from the windows being down. Above the ~50 mph mark, the drag from the windows being open outweighs the power loss of the Air Conditioning being turned on. Just got back from a weekend trip out of town... about 3/4 highway mileage this weekend with the majority of that being on the Interstate cruising with the windows up and the air turned on at the whopping speed of right around 63 mph... results: 388.1 miles on 18.01 gallons (tank filled to the top of the filler each time) = 21.5 mpg. Not Bad... especially for a 3.7L gas engine carrying the family and a fair load of gear aboard. Luis Turns out I was somewhat mistaken... the difference DOES weigh in favor of windows down and AC off until the speeds become much higher (~80+?) and the drag of the windows being down surpasses the HP loss of the engine to the compressor. My last highway trip was 318.3 miles using 13.244 gallons of gas doing 60 mph with the windows down and resulted in 24 MPG. Luis[/b]

Author:	FlaJeepDiver [ Tue Sep 27, 2005 3:13 pm ]
Post subject:	Re: Windows Open VS Air
Open the back window at highway speeds it will cut down on the drag. If you keep the back window closed it acts like a parachute. Just kidding, never ride with the window open. close windows at highway speeds. Open at local speed so you can make cat calls at pretty Jeepettes. Yes the A/c does drain power, but how often are you going up hill at 70mph? rlitchfield wrote: I'm a relatively new Liberty owner, and I’ve been reading these boards for some time now. An amazing amount of information is sitting in these boards for a “newbie” like myself. With the price of fuel around 1.30 CDN a litre I am watching my driving very closely. I have wondered something since I got my new wheels; what is better for better mileage, windows open, or air conditioner on. And does this “formula” change if I’m driving in the city or on the highway.