What’s more fuel efficient: driving with the air conditioning on or with the the windows down?
When it’s hot outside, an air conditioning system becomes your best friend. In a car, where temperature can rise to 170 degrees, it becomes your life saver. But when it comes to saving gas, is it more fuel efficient to keep the windows down or to keep the air conditioning running?
It’s obvious that keeping the windows done while you’re driving causes drag and keeping your air conditioning on puts more work on the engine, which both having a potential in burning more gas. Let’s take a look at both separately.
Is it air conditioning?
The air conditioning requires mechanical power to turn a compressor. In a car, the compressor is driven by a belt driven by the engine. Turning it on would put resistance on the compressor and against the car’s engine. Naturally, this would need to use more gasoline because the engine received some additional work.
Is it windows?
Whether it’s manual or automatic windows, rolling it down will cause drag. What is drag? Drag is the air pushing the car back caused by the vehicle moving forward. The engine at high speeds, like the air conditioning’s compressor, is getting additional work to maintain its speed.
Both the window and the air conditioning has potential to waste gas. So, what’s the solution? a mixture of both.
Based on a study by the Society of Automotive Engineers (SAE) , keeping the windows down and the air conditioning off at low speeds (45 mph or below) prevents a decline in fuel efficiency. However, at higher speeds, it’s best to roll the windows up and turn the air conditioning on. The reason being is that the drag at higher speed is almost four times as much compared to low speeds of 45 mph or less.