Will rolling down windows save fuel
or not? |
| By Dani
M. Arthur • Bankrate.com |
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Red Sox versus Yankees. Seat up versus
seat down. Microsoft versus Apple. To the list of issues people feel
irrationally passionate about, add one more: Whether it's more economical
to drive with windows down or with the air conditioning on.
Gas prices are topping $4 a gallon across the nation,
and motorists want to know the truth about which will make their
tank of gas last longer.
Bankrate published a story
about 10 money-saving driving tips. No. 8 was innocent enough. We thought. It
said, "Go easy on the air conditioning. Roll down your car's windows and
let in the summer breeze. Using the gas-hogging air conditioning as sparingly
as possible will give your car's fuel economy a real boost. Air conditioning can
drag down your car's fuel economy by 10 percent to 20 percent. " It
was like we insulted people's mothers. Bankrate's e-mailbag
filled with letters from people adamantly disagreeing. It's
a proven fact, they all asserted, that driving with your air conditioning on is
more fuel efficient. The reason, our readers explained, sometimes
patiently, is that when you drive with the windows down, it creates greater drag
on the vehicle. The vehicle uses more power to combat the increased drag, hogging
even more fuel than if you simply drove with the windows up and the air conditioning
on. Drum roll, please!
Several
experts were interviewed to find out just who is correct. The results are unanimous:
Driving with your windows down and the air conditioning off
consumes less gas than having the windows up and the air conditioner running.
This is absolutely true -- that is, when you're cruising around town.
"When you're driving across town, in stop-and-go
traffic," says Frank Hampshire, director of market research with
the Automotive Aftermarket Suppliers Association, or AASA, "it's
more fuel efficient to drive with the air conditioning off, windows
down."
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| Poll: Which gets the best
mileage? |
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Consumer Reports' auto-test department
reports that the air conditioner reduces your car's fuel efficiency by up to 10
percent. So to achieve maximum fuel efficiency, motorists should avoid using the
air conditioner at speeds below 40 mph and travel with their windows down, explains
Gabe Shenhar, senior auto test engineer at Consumer Report's auto-test department."But
as your speed increases to 45 mph, or highway speeds," says Jason Toews,
co-founder of GasBuddy.com, "wind drag becomes an issue. Driving with the
windows down increases the drag on your vehicle, resulting in decreased fuel economy
by up to 10 percent. Drive at speeds over 55 mph with windows down and you'll
decrease fuel economy by up to 20 percent or greater." Shenhar
and Hampshire agree: It's all in your speed. Tips
to cool your vehicle down
There are a few ways to cool your vehicle
down faster -- and cheaper -- during the hot, summer months:
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Tips | |
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Different cars react differently, and so the point
at which you should roll up the windows and kick on the air will be different
for each car. A 2004
study by the Society of Automotive Engineers found, for example, that the
aerodynamic drag for sport utility vehicles was particularly high, especially
the ones they drove on a test track at speeds above 100 kph. Automotive engineers
have all the fun. Or maybe not. During the test, one engineer
shot around the track with the air cranked up. A second had the windows down.
An unlucky third test driver was assigned to what turned out to be the most-fuel
efficient way to travel: Driving with the windows up and the air conditioner switched
off.
More: Reader reactions, poll, sound off!
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