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Effect of aircon on fuel consumption: A personal account

By SYF77 on 13 Feb 2011

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The recent mornings have been extra cooling due to the rain. Hence, there was one morning when I decided to give my carís air-conditioning system a rest and drove with the windows down to work. Oh boy, was I pleasantly surprised. I managed to clock a fuel consumption figure of 14.5km/l as compared to about 11km/l on the same 5km route. That represents an improvement in fuel economy of more than 30%. I repeated the experiment on a few more mornings and the results were similar. I therefore decided to do some research on the topic.

Running your air conditioning at 50 percent capacity can consume an extra ten percent of fuel. Short trips will require more air conditioning power. For example, if you drive fifteen minutes to the bank on a hot day, you will have had the air conditioning on full blast to cool off your vehicle. It will have just cooled down by the time you reach the bank. Then you park your car for thirty minutes. In that time the interior car temperature will have risen again considerably. When you finish your errand, you must again have the air conditioning at full power to reduce the interior temperature. City driving with air conditioning will have the most significant effect on fuel efficiency and that affects a large majority of Singaporean. According to reports, if the vehicle has a small engine, the fuel consumption will be greater because the power draw from the air conditioner is relatively constant. This could explain why I experienced a 30% improvement in fuel economy with my aircon off as my car has a puny 1.4L engine. When the air conditioner is on, engine sounds louder and acceleration is less responsive as well.

I know it is tough in Singapore but do try to turn off the air conditioner whenever you can, if you wish to spare a though for your wallet and environment. Plan your trips or chores in the mornings or evenings when it is cooler, in order to reduce stress on the air conditioner. Lower the windows to get a cool breeze into the car when driving on the highway in the morning. While you might create a slight drag with opened windows that marginally lowers your fuel efficiency, this is offset by the much greater amount of gas an air conditioner would consume. You can also reduce your speed slightly on the highway to counteract the drag. If you are worried that your hairdo will be messed up at the end of the trip, I recommend lowering the set of windows on the passenger side (both front and back).

The price of crude oil has hit USD 102 per barrel recently. If you wish to save on fuel and are willing to forgo a little comfort, do try giving your aircon a break. Do share your findings on this blog!

aircon, fuel economy and 2 more...

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Written by SYF77
I have been a car fanatic since 1989, when my father was changing our family car then to a Toyota Corolla 1.6 GL fitted with a Twin Cam 16 valve engine that was carburetor-fed, a big deal back in those days. The automobile technology and industry fascinates me and I hope to broadcast these interesting developments to everyone out there through this blog.

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Good-Carbuyer Feb 14 2011 09:42 AM
Many years back, while driving to KL with Octane 92, I noticed Uno without piston slap and better acceleration without using the car air-con
Jamesc Feb 15 2011 08:48 AM
1.4l car only doing 11 km/l?

What car is that?
SYF77 Feb 15 2011 01:50 PM
It's a Jetta Sport, on a 5km short trip.

Ruykava Feb 16 2011 03:26 PM
Unless it's raining, I haven't turned on my car aircon since I bought it! The blast of natural air in the morning helps me wake up, harhar.
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