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The AC in your car may be using more gas than you think; here's what you can do to save money

The Environmental Protection Agency and Department of Energy says running your AC in high heat can reduce your fuel economy by as much as 25%.

MINNEAPOLIS — We all know that running the air conditioner in your home can be expensive during the hot months of summer, but you might not think of the AC in your car.

In many vehicles, the air conditioning system uses gasoline to cool you down.

With gas prices the way they are right now your AC may be costing you more money this summer.

"Especially when gas is almost five bucks a gallon,” Dunwoody College of Technology automotive instructor Steve Reinarts says.

"A lot of things can affect the efficiency of your AC, your driving habits, how you drive, the model of the vehicle, the make, the engine."

Reinarts says there are so many factors that can affect how much gas your air conditioner uses.

He says some studies suggest that newer AC systems in newer vehicles will drop your fuel economy by 3% to 12%.

However, the Environmental Protection Agency and Department of Energy says running your AC in high heat can reduce your fuel economy by as much as 25%.

For a car that typically gets 30 miles to the gallon, that's like losing seven and a half miles.

For a 16-gallon tank it's like losing four gallons of gas, which these days could cost you nearly $20.

"If you're trying to save mileage, you're giving up a little bit of comfort,” Reinarts says.

That’s the tradeoff drivers will have to make this summer.

Reinarts says the best way to save gas with your AC is to just not use it, or not use it as much, or at least not use it in low efficiency situations like being stuck in stop and go traffic.

"Stop and go traffic there is a lot of underhood temperature that takes place from sitting behind another car that has exhaust dispelling a lot of heat. Also, you have a black pavement that's giving off a lot of heat,” Reinarts says.

Sitting idle will also put more strain on your AC, because the AC system works by drawing in clean air to help cool your vehicle.

When your vehicle is moving there’s a natural flow of air that takes some of the pressure off the AC system.

“When your vehicle is stopped the AC has to draw that air in on its own and that requires more energy,” Reinarts says.

That clean air also has to pass through a filter, and depending on how clean or dirty your filter is that can also affect the efficiency of your AC.

"Just like your furnace in your house, you have a furnace filter, you're going to have a cabin air filter inside your car,” Reinarts explains.

Changing that filter out twice a year will keep your AC running smoothly and will save you some money.

Reinarts also recommends that classic tip of parking your car in the shade when you can, it really makes a difference, so does a sun shade you can attach to your windshield.

"The sun shades work really well, because that's where your biggest sun load is on your windshield. That sun is bearing down on your windshield and it heats that car up pretty quick,” Reinarts says.

And when you turn on your AC, do it gradually.

Let's say you crank it down to 60 degrees and it gets too cold.

Well, then you have to dial it back up to something like 68 or 70 degrees, but if you do that, Reinarts says your vehicle will turn on the heater to warm things up.

Switching back and forth like that uses a lot of energy.

So, it's better to just cool it down gradually.

Reinarts says his best piece of advice is to fight the urge to turn on your AC the moment you step into your vehicle.

Instead, he recommends opening all the windows and driving your vehicle for a few miles to kick out the hot air that has been lingering in your vehicle all day.

Once that hot air has a minute or two to get out of your vehicle, then you should close the windows and turn on your AC.

If you use this technique, Reinarts says your AC won’t have to work as hard to cool your vehicle and you won’t have to spend as much money on gas.

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