Which is more economical: cooling with rolled down windows or AC?

Dear Car Talk

Dear Car Talk | Nov 01, 1995

Dear Tom and Ray:

I have a question about car air conditioners. Does it save gas to (a) just roll the windows down and forget that you have an air conditioner or (b) keep the windows up (which cuts down on air resistance) and use the air conditioner which you paid dearly for in the first place? My vote is to keep the windows up and use the A/C. What do you say?

TOM: We're with you, Irene. And so is the Society of Automotive Engineers (SAE).

RAY: Believe it or not, SAE published a detailed study which showed that at highway speeds, it is more economical to use the air conditioner and keep the windows closed than it is to forego the air conditioner, and drive with the windows open. How's that!

TOM: They said that the gasoline you save by maintaining the car's aerodynamics (keeping the windows closed) more than makes up for the extra gasoline used to power the air conditioner. And they didn't even take into account the unforseen costs of driving with the windows open, like the extra visits to the hair dresser, Irene!

RAY: This study was done several years ago, and because cars' aerodynamics have improved since then, my guess is that SAE's findings are even more true today than they were then. So roll 'em up and drive comfortably, Irene.

TOM: And tell that fat-headed husband of yours to stop bothering you about using the A/C (we're reading between the lines of your question here, but we're right, aren't we?).

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