Welcome to summer where July and August are the hottest times of the year with September being humidity-filled as well. However June can surprise us with heat waves, too.

Driving with the windows down on a beautiful day is heaven however when it's just too hot it's complete misery and it's air condition time.

I've always heard that using the AC doesn't use that much gas so I never really paid attention. However a colleague told me she always heard just the opposite so she keeps her windows down as long as she can until it's just too uncomfortable to drive without AC.

Car air conditioning system. Air condition switched on maximum cooling mode

Well, research seems to say that we're both correct depending on the situation.

We have a much higher fuel consumption under extreme heat when the AC is on. Other than that, using the AC doesn't use enough to make a differenced according to the Family Handyman website.

Running your car’s air conditioning does increase fuel consumption, but the specific amount can vary widely depending on several factors. The effect on gas mileage can be as little as 3% to as much as 25% in severe conditions.

The AC draws power from the engine's alternator, which runs on fuel but for the most part not enough for us consumers to notice an affect on our spending.

Meanwhile this is something I never thought about.

On the highway where we're driving at much faster speeds we use more gas with the windows down than with the AC.

car road trip, person sitting on front seat and raise hand out from window

Who knew?

When the windows are up, the vehicle is more aerodynamic. When the windows are down, this creates excess drag on the vehicle, which increases resistance and makes the engine work harder.

Also, according to Family Handyman, stop-and-go city driving is tougher on the engine when the AC on so we use a bit more fuel. In contrast, highway driving plus AC will virtually have no impact on fuel consumption.

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