Saving Gas: Should You Drive with Air Conditioning on or Windows Down?

Arguments raged, voices grew louder, yet neither of my parents would budge on the issue. One said having the windows up and the air conditioning (AC) on saved money; the other thought wide open windows and no air conditioning was more cost effective. Times and technology may have changed by the seemly age old argument rages on. So which is the most cost effective way to save gasoline costs while driving.

According to Stanford University School of Earth Sciences - Earth Systems Program this seemingly simple question still does not have a conclusive answer. There are some things that were able to be nailed down. Using AC lowers fuel economy of your vehicle at whatever speed you are traveling. Lowered windows decrease fuel economy by increasing drag. So perhaps the question that should be asked is at what speed does the drag, overcome the gain of having forgone the use of the AC system.

At the Society of Automotive Engineers, they found that all cars were more efficient with the AC off and windows down when speeds were low. However, when speeds approached 65 mph the difference was basically insignificant. Their recommendation was having windows rolled down for all driving except highway driving. For highway driving they recommended AC use. If you and your partner are still arguing and need the charts, bells, and whistles to prove your particular point, go to the actual study at www.sae.org .

ANNOYANCES

If you have those pesky, troublesome annoyances, the ones that nag constantly, the cost of using the AC may be a small factor in determining your choice of AC vs. rolling-down-windows. These annoyances include asthma, hay-fever, other allergies, and children. Or perhaps, in the case of the latter you may need a breath of fresh air, time in the country or the loony bin. Your choice...your child. Perhaps, your child needs left behind. Hm...it would decrease the drag, but I digress.

TIPS

Stanford University School of Earth Sciences - Earth Systems Program website offers additional "green tips" for running your car in an economic and eco-friendly manner.

They suggest leaving your AC off and using vents when possible. If AC is being used, have the setting on re-circulate air. Their other suggestion is to use the AC in short bursts rather than leaving on constantly.