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How-to guide · Michigan City Ford · Michigan City, IN
Does AC Use Gas?
Running the air conditioning does use fuel. Here is what fueleconomy.gov says about how much, when open windows make more sense than the AC, how idling with the AC on adds up, and how to stay cool while using less fuel or battery power.
25%+possible fuel economy reduction from AC use under very hot conditions, per fueleconomy.gov
1/4 to 1/2gallon of fuel an hour that idling can use, depending on engine size and AC use
Highwayspeeds are where fueleconomy.gov says to use the AC instead of open windows
LargerAC effect on hybrids, plug-in hybrids and EVs on a percentage basis
The short answer
Yes. Fueleconomy.gov says running the air conditioning is the main contributor to reduced fuel economy in hot weather. Under very hot conditions, AC use can reduce a conventional vehicle's fuel economy by more than 25%, particularly on short trips, and the effect on hybrids, plug-in hybrids and EVs can be even larger on a percentage basis. Roll the windows down at lower speeds and use the AC at highway speeds.
How much fuel the AC uses
The AC is the main factor in hot weather. Fueleconomy.gov says running your car's air conditioning is the main contributor to reduced fuel economy in hot weather.
It depends on conditions. The effect depends on a number of factors, such as the outside temperature, humidity and the intensity of the sun. Under very hot conditions, AC use can reduce a conventional vehicle's fuel economy by more than 25%, particularly on short trips.
Hybrids and EVs feel it more. The AC's effect on hybrids, plug-in hybrids and electric vehicles can be even larger on a percentage basis.
Heat itself is not the problem. Hot weather can actually increase fuel economy: the engine warms up to an efficient temperature faster, summer grades of gasoline can have slightly more energy, and warm air causes less aerodynamic drag than cold air. Keeping passengers comfortable with the AC or open windows is what can reduce it.
From fueleconomy.gov, Fuel Economy in Hot Weather, read November 8, 2026, which cites SAE technical papers and Oak Ridge National Laboratory research.
AC or open windows?
Open windows add drag. Fueleconomy.gov says driving with your windows down can also reduce fuel economy, because open windows increase aerodynamic drag (wind resistance) and the vehicle uses more energy to push through the air.
Speed decides. That effect is quite small at low speeds but increases at highway speeds. So the advice is to roll the windows down at lower speeds and use the AC at highway speeds.
From fueleconomy.gov, Fuel Economy in Hot Weather, read November 8, 2026.
Idling with the AC on
Idling burns fuel. Fueleconomy.gov says idling can use a quarter to a half gallon of fuel per hour, depending on engine size and air conditioner use, and that it only takes about 10 seconds worth of fuel to restart your vehicle.
Cool down while driving instead. Do not idle with the AC running before driving. Turn the AC on after you begin to drive or after airing out the cabin briefly; most AC systems will cool the vehicle faster while driving.
From fueleconomy.gov, Driving More Efficiently and fueleconomy.gov, Fuel Economy in Hot Weather, read November 8, 2026.
Tips to use less fuel with the AC
Fueleconomy.gov suggests these steps to improve fuel economy in hot weather:
| Tip | Why it helps |
|---|---|
| Roll the windows down at lower speeds; use the AC at highway speeds | Open windows add aerodynamic drag; the effect is quite small at low speeds but increases at highway speeds |
| Do not use the AC more than needed or set the temperature lower than needed | AC use is the main contributor to reduced fuel economy in hot weather |
| Park in the shade or use a sunshade | The cabin does not get as hot |
| Drive with the windows open for a short time before using the AC | Letting hot air out first puts less demand on the AC and helps the vehicle cool faster |
| Do not idle with the AC running before driving | Most AC systems cool the vehicle faster while driving; turn the AC on after you begin to drive or after airing out the cabin briefly |
| Read your owner's manual | Most manuals explain how the AC controls work and how to best use and maintain the AC system |
| Plug-in hybrids and EVs: pre-cool while plugged in | Pre-cooling the cabin while plugged into the charger can extend range, and a warmer AC setting uses less battery power |
From fueleconomy.gov, Fuel Economy in Hot Weather, read November 8, 2026.
Service at Michigan City Ford
The Works® at Michigan City Ford includes a synthetic blend oil change, tire rotation and pressure check, brake inspection, Multi-Point Inspection, fluid top-off, battery test, and a filter, belts and hoses check. Fueleconomy.gov also suggests reading your owner's manual, which explains how the AC controls work and how to best use and maintain the AC system.
Schedule service online and see our service specials first. Michigan City Ford is at 3930 Franklin St. in Michigan City. Get directions.
Michigan City Ford service hours
| Days | Hours |
|---|---|
| Mon-Fri | 7:30 a.m.-5:30 p.m. |
| Sat | 8 a.m.-3 p.m. |
| Sun | closed |
From Michigan City Ford's website, November 8, 2026. Holiday hours can differ.
AC and gas mileage FAQ
Does running the AC use gas?
Yes. Fueleconomy.gov says running your car's air conditioning is the main contributor to reduced fuel economy in hot weather, and under very hot conditions AC use can reduce a conventional vehicle's fuel economy by more than 25%, particularly on short trips.
How much does the AC affect gas mileage?
It depends on a number of factors, such as the outside temperature, humidity and the intensity of the sun, according to fueleconomy.gov. Under very hot conditions the reduction can be more than 25% for a conventional vehicle, particularly on short trips.
Is it better to use the AC or roll the windows down?
Fueleconomy.gov's advice is to roll the windows down at lower speeds and use the AC at highway speeds. Open windows increase aerodynamic drag; the effect is quite small at low speeds but increases at highway speeds.
Does the AC use gas when the car is idling?
Fueleconomy.gov says idling can use a quarter to a half gallon of fuel per hour, depending on engine size and air conditioner use. It suggests not idling with the AC running before driving, because most AC systems cool the vehicle faster while driving.
Does the AC affect hybrids and electric vehicles?
Yes. Fueleconomy.gov says the AC's effect on hybrids, plug-in hybrids and electric vehicles can be even larger on a percentage basis. Pre-cooling the cabin while plugged into the charger can extend a plug-in hybrid's or EV's range, and a warmer AC setting uses less battery power.
Does hot weather hurt fuel economy?
Not by itself. Fueleconomy.gov says hot weather can actually increase fuel economy: the engine warms up to an efficient temperature faster, summer grades of gasoline can have slightly more energy, and warm air causes less aerodynamic drag than cold air. Keeping passengers cool with the AC or open windows is what can reduce it.
What does The Works at Michigan City Ford include?
The Works® at Michigan City Ford includes a synthetic blend oil change, tire rotation and pressure check, brake inspection, Multi-Point Inspection, fluid top-off, battery test, and a filter, belts and hoses check.
Questions about a new Ford?
Talk with the Michigan City Ford team, or read our guide to getting better gas mileage.
Sources
How air conditioning and open windows affect fuel economy, and the tips, are from fueleconomy.gov (U.S. Department of Energy and EPA), read November 8, 2026. The idling and restart figures are from its Driving More Efficiently page, read the same day. Service details, address and hours are from Michigan City Ford's own website.
- fueleconomy.gov, Fuel Economy in Hot Weather, fueleconomy.gov (U.S. DOE/EPA), read November 8, 2026
- fueleconomy.gov, Driving More Efficiently, fueleconomy.gov (U.S. DOE/EPA), read November 8, 2026
- General service: The Works, Michigan City Ford, November 8, 2026
- Address and service hours (structured data), Michigan City Ford, November 8, 2026