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Air Conditioning: Does It Really Burn Gas?

In the hot weather, air conditioning is a necessity, especially in a vehicle. However, it has become a common myth that running your vehicle’s air conditioning burns more fuel. Consumers have become more considerate of fuel efficiency, because of the high gas prices. Well, there’s no need to ride in a hot car for the sake of saving on gas. It’s been proven that running the air conditioning does not have a large effect on fuel efficiency for modern cars. Leaving the air conditioning off makes little difference, unless you have a sunroof. Even with the air conditioning off and the sunroof open, there won’t be a significant difference in gas mileage. Has the air conditioning myth been proven wrong? Modern cars make it okay to drive with the air conditioning on.

The A/C compressor pulls power from the engine wasting some gas, the effect appears to be minimal in modern cars. The A/C can lower the fuel efficiency from 10 to 20 percent depending on the type (and age) of your vehicle. Using the air conditioning does require your vehicle to burn more fuel, but it is more efficient than driving with the windows down. Putting the windows down is not a good idea. Putting the windows down tends to increase drag on most cars, canceling out any measurable gain from turning the A/C off. The increased drag of the car means your vehicle will have to work harder, because of the change in the aerodynamics. Therefore, open windows cause your car to burn more fuel.

If your considering fuel economy, it is okay to use your vehicle’s air conditioning. Yet, it should be used sensibly. If you’re driving around town, or in city traffic, then you’re better off leaving your windows open. For highway driving, roll the windows up and turn the air conditioning on. It’s advisable to roll the windows down for city driving, because speeds lower than 30 – 40 mph vehicles consume less fuel, then using the A/C at those speeds. Using the A/C at highway speed has no appreciable effect on fuel economy compared to rolling down the windows.

When entering a hot car, roll the windows down to bring the temp down, and allow the hot air to briefly blow out. Putting the A/C on “re-circulate”(often max cool), helps the vehicle’s cool down period. The higher setting won’t have any affect on the fuel efficiency. Once the car is properly cooled, turn it off again. The A/C should not be needed again, unless traveling at speeds above 40 mph, but don’t roll the windows down.

Using the air conditioning doesn’t make your car more efficient, but varying usage of the A/C can work when trying to improve fuel economy. It’s already been established that having the windows open at lower speeds, and having them up with the A/C on is the most efficient usage. However, the most fuel-efficient vehicle is one with the windows rolled up, and the air conditioning off. For the greatest fuel savings leave the windows up, and use the vehicle’s flow through air vent system. It seems this method is better than having the air conditioning on, but using the air conditioning is still more fuel efficient than driving with the windows down.

Modern cars are designed aerodynamically to cut resistance and boost efficiency. Open windows increases fuel consumption, because an open window causes more wind resistance. Vehicles like SUVs aren’t inherently aerodynamic, so they would be better with the windows up, and the air conditioning on. On the other hand sedans have less drag than SUVs. So, the rule of driving with the windows up and A/C off is best for sedans. So, air conditioning usage can depend on what type of vehicle you have.

It has been a common misconception that not using the air conditioning in your vehicle will increase your fuel economy. But, it seems many consumers have neglected to realize that driving with the open window burns more fuel. So, the myth cannot be called a myth, because the air conditioning does reduce fuel efficiency. However, consumers should know that the A/C doesn’t burn up that much fuel in modern cars. So, there’s no need to drive uncomfortably for the sake of saving money on gas.

thanks to Mawe for giving me this source

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