High gas prices tag teamed with the scorching summer months means people are doing clever things to avoid the inevitably notorious next trip to the gas pumps… well so they think.

Driving around on the busy California freeways, I have noticed that quite a few people have been driving around with their windows down. Now, it is no secret that using the air conditioner in your car comes at the expense of decreased gas mileage. But, the question is, are you really saving gas? When should you drive with the windows down vs. up with the air conditioner on if ever? What about when you are driving in the city at 40MPH vs. the highway at 70MPH?

Well here is the answer which some of you may be surprised by. Driving with the windows down while at highway speeds actually DECREASES your gas mileage! Yeah, you heard right, decreases! Why? Well because when you drive with the windows down at those highway speeds, you are introducing quite a bit of drag into the MPG equation. What does drag mean? Well in this situation, drag is caused by air outside flowing into your vehicle and because of that, making it more difficult for your vehicle to move forward. Imagine trying to run against a 70MPH wind. With your windows closed, your vehicle can retain it’s aerodynamics and literally slice through the air with less resistance.

What about at city speeds, say 40MPH on average? Well, in that situation, rolling the windows down vs. using the air conditioner may be to your advantage. The amount of gas you burn in the city by rolling down your windows is less than the amount of gas burned by using your air conditioner.

Granted, when driving short distances, either windows down or air conditioner on will make only make marginal differences. But, across longer drives, choosing the correct option can yield a trip to the pump later rather than sooner.

I hope this saves you a few bucks. Be sure to let everyone know! Who knows, if enough people start doing their part to be more efficient, we might be able to see gas price stability!

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