Does it use more gas to drive with a/c on?

For best MPG:

HWY speed – AC on and window up.
STREET speed – AC off and window down.

The BEST – AC OFF and window UP.

I was out today and was just going for a short drive. The above was kind of moot because it was so hot I could not drive with the AC off (which I normally prefer – regardless of cost).

Good Luck…

It depends on the speed you are going. If you are going over 40 miles an hour, the air resistance caused by having your windows down causes you to get less miles per gallon. Under 40 miles an hour, it makes sense to roll your windows down.

No, not compared to the windows rolled down and the wind resistance holding back the car.

with modern ac’s using less energy, the answer I’ve been hearing and reading is no, and this is just today in the Asbury Park Press.

Yes. The engine has to work harder. But do not go with out ac. I did that for a year, because my boyfriend told me that, and i almost died in the summer, especially in southern California.

oh yeah. it most certainly does. probably 10 – 15 percent would be my estimation

yes the a/c puts more stress on the engine causing it to use more gas however most modern cars get better gas mileage with the a/c on than with the drag they experience with the windows down. so its better to drive with a./c than windows down but a/c uses more gas than no a/c with windows up. I hope that helps.

Yes, when the AC is engaged it puts more strain on the belt/pulley system which adds more strain to the motor. More strain to the motor requires the motor to run harder, therefore using more fuel. Newer vehicles are more efficient but you still use more fuel with the AC, though it may be a smaller amount than an older vehicle.

Using air conditioning does decrease your fuel mileage slightly. Depending on the type of vehicle you drive, this decrease may only be 1 or 2 mpg.

On the other hand, if you were really in danger of running out of gas, your car would have given you an indication. Some cars will give a warning light, others will alert you that you have a certain amount of miles left before you are out of luck. So, unless this was the case, turning the A/C off was unnecessary.

But, the answer to your question is yes. Use of air conditioning, just like having the windows down, decreases fuel mileage.

On average, it will reduce your milage by 1 mpg. When you drive with the windows down instead, the wind resistance on your car also decreases the milage by 1 mpg.

Yes.

the air conditioner has a belt-driven “compressor”. It requires energy to turn the pully with the belt that drives the compressor. It puts a bigger load on the engine. The engine makes fewer RPMs at the same throttle setting, so you have to “give it more gas”.

Turning the A/C on does put a load on the engine, therefore using more gasoline. The A/C is belt driven off of the engine. Just depends on the engine how much it loads the engine. 4 cylinders will use more gas, V8′s have more horsepower that the A/C will not load it very much.

I’ve always understood that to get good mpg the following applies to air con;
If it’s hot, roll a window down.
If it’s very hot, roll both windows down.
If your steering wheel’s melting put your air con on.

Sometimes! According to Wikihow (see link below for more ways to save)
Use A/C only on the highway. At lower speeds, open the windows. This increased the drag and reduces fuel efficiency, but not as much as the AC at low speeds (35-40 mph).
Happy motoring :>)