I haven't noticed any difference in MPG with and without the A/C. I have done the same drive (to/from Vegas) on severeal different occasions and sometimes had the A/C on - other times did not. I always fill up at the same gas stations when leaving and coming back and pretty much always within a 1/4 of a tank variance, which I've generalized by how much stop and go I had to deal with.

It seems logical that A/C usage should matter, but I am yet to notice any significant difference.

Anyone who knows anything about how an air conditioner works or, for that matter, anything about basic engineering or physics knows better. The AC compressor consumes energy, and that energy comes from your gas tank. All due respect, whoever wrote this is either a moron, cares not a bit about the truth, or both.

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2002 X5 3.0i

One other myth of myths is saying that driving a vehicle with the windows open does not effect fuel consumption. Somehow this defy's common sence. For example:

Consider the way cars are designed today. With all the engineering effort to expended to reduce drag It's only logical to conclude that a car with the windows down produces a great deal more drag then one with the windows up. Further the more windows that are open on the sides of a car, the more drag is present. This decreases somewhat if the back or 'moon roof' windows are open on different faces of the car, because they allow air to flow through the car. Still, the drag is more than that of the closed car, because the air slows down considerably once it enters the car and hits seat, you, your dog, or other obstacles. IMHO It's just common sense.

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"What you hear in a great jazz band is the sound of democracy. “The jazz band works best when participation is shaped by intelligent communication.”
Harmony happens whenever different parts get to form a whole by means of congruity, concord, symetry, consistency, conformity, correspondence, agreement, accord, unity, consonance…….

It was on my yahoo homepage

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The article says that edmonds did a study on the fuel economy with A/C on/off and the windows up/down and found no 'significant' impact (not that there is 'no' impact at all).

I think one of the reasons the windows and A/C myths are so commonly believed is because they seem to make logical since. Taking a step back and thinking more about it, it does make since that there would be 'minimal' impact on the fuel economy on a car that has a 200hp, 300hp+ and other high hp engines.

I'm by no means a engineer nor have ever done any kind of first-hand research on this. But based on my past experience, I mentioned in earlier post, and considering what they say about not a 'significant' impact, it seems very reasonable to me.

So does this justify when cabs charge an extra $1 "AC surgcharge?" Bah.