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When you turn on your A/C in the vehicle, a small clutch on the pully engages and starts making the engine turn the pully. Having the extra load to turn will cause more fuel consumption.
In most modern cars it's more efficient to use the A/C instead of rolling down your windows. This was tested by "Mythbusters:"
"it is more efficient, on a hot day, to run with the A/C on and windows up than to run with windows down (b/c of increasing car's drag).
Computer-based mpg measurements: * 11.7/11.8 with A/C on and windows up * 11.7/11.8 with A/C off and windows up * 11.3 with A/C off and windows down
So, according to the computer, it's better to use A/C with windows up."
Source: http://kwc.org/mythbusters/2004/11/mythbusters_boom_lift_catapult.html
What many people don't realize is that the A/C also runs whenever you use the defroster. Even when it's the dead of winter -10 degrees and the temp knob is all the way to hot, the A/C still engages.
The concept is to dry the air before it blows on the windshield.
Of course, the amount only depends from car to car, but using A/C requires consumption of gasoline.
you want cool air, you gotta use more gas!
Don't have an answer for you legs! But i learned a lot from your other answers! So Thank You for your Question!
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You're reading How does using the A/C in your car affect your consumption of gasoline?
Comments
Okay, I think I get it now, thanx Spicy and +6 for you.
by chickenchaser on July 22nd, 2009
Your welcome LongName. :-)
by Spicy Hot on July 22nd, 2009
serpintine belt
by The Wraith of God is Coming on July 22nd, 2009
Thank you. :-)
by Spicy Hot on July 22nd, 2009
Note: The amount of additional fuel consumption is relatively small. A typical A/C compressor requires about 5 horsepower to run. Most modern cars (even small 'economy' cars) have 120hp+ engines, so the additional load of the A/C does not strain them much.
by Old School on July 22nd, 2009
So I shouldn't really worry about it then, right? I should just stay cool instead of suffer in the heat.
by chickenchaser on July 22nd, 2009
Old School, I have heard that it it reduces your gas mileage by 2-3 mpg. Do think that is accurate?
by Spicy Hot on July 22nd, 2009
You should not suffer in the heat.
by Spicy Hot on July 22nd, 2009
@SpicyHot - It's difficult to put a firm number on the MPG loss, because it depends upon so many things.
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For example, if you drove at a steady 65 mph, it takes about 20-25 hp to keep your car at speed. Let's say that takes 10% of maximum throttle. Turning on the A/C raises that to say 12% of maximum throttle. I doubt the mileage loss would be detectable.
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Conversely, if you're stuck in stop-and-go traffic, your engine mostly runs at idle (let's say 1000 rpm). If you turn on the A/C, the engine spends a lot of time at 'fast idle' (let's say 1500 rpm) to provide enough power for the A/C compressor. Then you'd probably notice a significant drop in fuel economy.
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At the end of the day, fuel economy loss due to A/C use is normally quite small. Other factors (engine tune, tire pressure, driving style, terrain, etc.) have much more influence on fuel economy than the A/C does.
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Go ahead and stay cool (drive 5 mph slower if you're worried about fuel economy).
by Old School on July 22nd, 2009
Thanx so much Old School, I have learned a LOT today. I am glad I asked this question.
by chickenchaser on July 22nd, 2009
@LongName - You're welcome. Such compliments are always nice to see.
by Old School on July 22nd, 2009
Thank you very much Old School.
by Spicy Hot on July 22nd, 2009