What's more fuel-efficient, driving with A/C or with windows open?

Question

Increased fuel needed for A/C versus open window drag.

Answer 1

You obviously didn't see the "Mythbusters" episode where they definitely proved that it's more fuel efficient driving with the A/C on and the windows up.

Answer 2

I saw a study on this very question and it is more efficient to drive with you windows up and you A/C running.

Answer 3

there's no differance. the ac compressor adds resistance to the motor which sightly decresses mileage, but driving with the windows open adds parasitic drag which equally reduces mileage.

Answer 4

It's a close call, which depends on the speed you're going, the particular car, how many windows how far down, etc.

Do what you like and don't worry about it.  It's too small a difference.

Answer 5

windows UP & ac ON.

Answer 6

Depends on how fast you're going.

At high speeds then you should put the windows up and turn the AC on while low speeds are better with the windows down and AC off.

It also depends a lot on your car, newer cars have more efficient air conditioners than older ones.

Answer 7

Myth Buster's did a show on this exact situation not too long ago.  Driving with your A/C on saves more gas.

Answer 8

When traveling under 45-50 MPH, it is more fuel efficient to drive with the windows down.

When traveling 50+MPH, the windows being down creates drag, making the A/C the more fuel efficient choice.

The intensity of the air conditioner also plays a part in the equation. Be reasonable, you're not a snowman. Pardon my rudeness if you are.