The Fuel-Use Debate - Car AC or Windows Down?

There is a school of thought that claims your car AC is a huge drain on your car engine and that it has a noticeable effect on your fuel usage. Another group claims that car air-conditioning is actually very efficient and that the drag caused by open windows is a larger detriment, especially on the highway. So, how much does the AC affect gas mileage as opposed to open windows, and what factors do you actually have to consider when making the calculations?

Using Air-Conditioning

As is to be expected, there are documented advantages and drawbacks to either choice. To be able to weigh the two properly, you need to know the pros and cons of using air-conditioning or climate control.

Rolling Your Car Windows Down

Then there's the alternative. Sometimes, you don't need a high-tech solution to a problem, when a more analog one can do the same job. Still, there are reasons we create technology to perform seemingly mundane tasks, so what's actually good and bad about driving with the windows down?

Tips on How to Cool Down Your Car’s Interior Quickly

If your car has been standing in the sun for hours and feels like a sauna when you get in, try the following:

• Open all the windows immediately
• Start driving to let the car air out
• Set the air-conditioning to cold
• As soon as air-conditioned air arrives, close the windows
• Don't waste fuel by driving with both an open car window and the air conditioner operating

How Much Does the AC Affect Gas Mileage?

Luckily, there have been multiple studies on this particular subject, so there is a fair amount of data corroborating the findings. Using your air-conditioning uses more gas than opening your windows, especially in city traffic or when driving slowly. At speed, open windows' added drag plays an increasingly important role, but it still wastes less fuel than using the air con. So, how much gas does the AC use? Up to 25% more, especially on short trips. So in the battle of air-conditioning up vs windows down, open windows are better for fuel economy.

Conclusion

What is the moral of the story? Open your windows whenever you can and only use your air-conditioning when you have no other choice, such as on the open road, when nothing else cools you down, or in dusty conditions. This is the best way to save fuel while still enjoying the benefits of air-conditioning when you need it, as permanently leaving the air-conditioning on wastes gas.