Turn off the AC - save a bit of fuel
Every little bit helps, so turn off the AC when you're not really using it to full advantage. It could save you many gallons per year, but you probably won't notice much per tankful of fuel. Nevertheless, all gasoline saving tips are cumulative.
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Turn off the AC. With newer cars, the AC compressor runs intermittently, so it has less adverse effect on fuel economy. Nevertheless, you can get better gas mileage if you use the AC only when necessary.
Using AC only when necessary and having a focus on getting better gas mileage means that you leave the windows rolled up at highway speeds and rolled down if you are cruising around town. The drag created by open windows at highway speeds is about the same as running the air conditioner. At around town speeds, the effect of drag is much less.
You can also stretch the AC a bit by turning it off about a mile or so from where you intend to stop. The heat exchanger (chiller) is still plenty cold and will continue to cool the air in your car for several minutes, even with the AC shut off and the fan left running.
Also, put your air system on recirculation. This cools inside air over and over again, instead of trying to cool outside air that is naturally much warmer.
On older model vehicles, better gas mileage is affected more since the AC compressor runs all the time when you make a demand for AC. So, if you turn off the AC, you'll save considerably more than with a newer car.
If you don't know what kind of system you have, turn on your car and your AC, lift the hood and listen for a few minutes. If you hear something clicking and running for a few seconds every 30 seconds or so, then you have a newer style air conditioning system.
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