AC vs Open window.

---MIKE---

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According to Mythbusters, it is more economical to open the window than run the air conditioner. I enjoy the show and they seem to be pretty good at analyzing the physics of the myths and urban legends they are investigating, but in this case, I thought that they were not very scientific. They used a Ford Expedition, and while it has a powerful, engine, it is not very aerodynamic, they used 2 different drivers, and their method of trying to put the same amount of fuel into the 2 vehicles was flawed. Even so, their demonstration showed that the vehicle with the window open got about 2 tenths of a mpg better fuel economy.

IMO, a more aerodynamic vehicle like a passenger car will get about the same MPG with the windows open or the AC on at highway speeds but better MPG with the window open in stop-and-go driving.

I wonder if they investigated the question of subsonics. As far back as the 70s, it was known that an open aperture (window, roof vent &c) in a vehicle moving at appreciable speed (dunno how fast that is, maybe faster than a human can easily run) can produce a _howl_ of noise inside at low frequencies we cannot hear but can be bothered by. The effect adds over time, causing a vague sense of discomfort, anxiety, irritation and similar.

But maybe more recent vehicle designs have done away with that.

They did not mention subsonics on that episode. Personally, driving on the highway with the window or sunroof open for a long time is tiring; I can drive a lot longer without all the wind howling, tire noise, etc.

It may be but and you may even save a few cents, but the only way to cool the inside of your vehicle and lower the humidly so that is comfortable, turn on the AC ;)

mike hunt

Or get rid of sweaty windbag passengers!