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Windows up or Windows down?

ok i always thought windows up with A/C on was better than windows down. The guys at mythbusters have said they have busted this myth watch this

Is this because they were going 45 mph instead of 70 mph?
I am going to ask same question at their website.

Car and Driver found that windows down beat windows up with A/C, too. But it’s 100 in Dallas, so I’ll be happy to buy an extra gallon of gas!

Texases is right. With the exception of a few hypermilers, people are going to do what’s comfortable for them.

The guys at mythbusters have not busted anything. This has been tested numerous times in the past, including by me, and the results have varied with type of vehicle, but none has shown any significant difference.

It’s vehicle dependent. Some cars are very aerodynamic and thus more prone to disturbances in their aerodynamics by lowering windows. Other vehicles have small wimpy engines and by turning on the AC puts a serious load on the system.

It all depends on the vehicle…there isn’t one answer that can be applied to all vehicles.

All I know is I’m a lot more comfortable in the Summer heat with the AC on…And the difference isn’t worth worrying about (if there is any).

A/C in a modern car is generally rather efficient.  There is little difference, so I like most choose to be cool and comfortable.  

It is not just the temperature, but with windows open the car is noisier, and you feel the buffeting.  I wears down the driver so that it actually can be a safety issue as well.

not to mention a health hazard too. The wind buffeting can cause hearing problems

I have no wind buffeting, is this a political correctness question? If you want the windows down, roll them down, if you want AC, run the AC. Are you afraid some green guy is going to pull up and holler at you for loosing a little mpg because you have your windows down? Or is sacrificing what you prefer worth a little better mpg? I am the worst of both worlds, sometimes windows down and ac on and I do not notice any significant change in mileage


Buffeting is a high-frequency instability, caused by airflow separation or shock wave oscillations from one object striking another. It is caused by a sudden impulse of load increasing. It is a random forced vibration. Generally it affects the tail unit of the aircraft structure due to air flow down stream of the wing.

I have been in some cars that buffeting is a problem, it is sincerely annoying!

Some cars buffet, some cars don’t. My '91 Camry would buffet your eardrums right out of your head if you only opened the rear windows. Owners simply learn how to adjsut their windows to provide air and prevent buffeting. The physics of buffeting don;t need to be understood to stop it from happening.

car and driver are nuts about the air vs. the windows. i guarantee using your air uses more fuel whether you have windows up or down, this is silly to believe their theory

well, going at high speed you must adjust your windows to keep your sanity, still better that wasting fuel by using air. unless u got plenty bucks to toss

I guarantee others have come to the same conclusion, scientifically (pop sci) All have said the same thing. It depends upon the speed, and yes, at higher speeds, it’s more efficient to use the air. (above 60 mph to be exact)

Jesslalone, C/D didn’t have a ‘theory’, they tested it and reported their measured results.

Does anyone here have any idea for how many decades this has been debated? The question has no single answer because the variables are almost unlimited. Vehicle aerodynamics, speed, engine, power train, AC system, everything makes a difference. I wouldn;t be surprized to find out that altitude, ambient pressure, and relative humidity affect the results.

I remember it coming up in the '70s, with the first gas price spike.

Yeah, I seem to recall discussing the subject with friends and reading “tests” in magazines many, many moons ago when I was a young fella.

Not only a health problem for the ear drums but if you are driving behind a turkey truck headed to the turkey plant, you can pick up some nasty diseases from them. All in all doesn’t matter.

I saw the Myth Busters segment on dimples on a car like a golf ball and that actually increased the mpg. Covered the whole car with clay and cut dimples in it. There are some lengths we will not go to for fuel economy.

Recent research indicates that most of the information I get from newspapers is lacking in accuracy. Rumors too. The above posts are a lot better than that.

I favor the windows down for better fuel economy but I landed in Albuquerque at night when the high temperature was 106 that day. I landed in the E-150 van I drove there from Victorville Ca. The AC kept the temperature down to about 79. Windows down at 110 degrees is fine if you’re 18 but you don’t want to do it if you’re 52.