Dear Car Talk:
Help! My wife and my adult daughter have taken up a practice that I’m concerned about. In the hottest part of the summer, they like to turn on the car’s air conditioning AND roll down the window!?!
They say they like the coolness, but also enjoy the fresh air. I say the car’s air conditioner is being excessively used and is killing their gas mileage.
Should I be concerned or just consider them nuts? — Mike
I do this, too, Mike. When it’s really hot out, there’s nothing I like better than having the AC vents blowing right below the belt and fresh air blowing on my face. Especially when driving around town. I just don’t like being cooped up in a hermetically sealed car.
Is it wasteful? Yeah. Having the windows down — at least at higher speeds — worsens the aerodynamics of the car, so it reduces your mileage. The air conditioner itself doesn’t necessarily work any harder, it’s either running or it’s not running. But your overall fuel use will go up.
How do I defend it? Not very well. I’ll confess that like many of us, I’m sometimes willing to give up a little efficiency in exchange for some comfort. I guess I’ll have to answer to St. Peter for that. And my electric utility.
But before you claim the moral high ground and go after your wife and daughter, Mike, make sure you’re not vulnerable to counterattack.
For example, you’re right that it’s more efficient, on the highway, to drive with the windows up and the air conditioner on.
But you know what’s even more efficient? Driving with the windows up and the air conditioner off. The girls may insist you model that exemplary environmental behavior if you insist on being the moral arbiter of their energy use.
And speaking of the environment, if you go that route, Mike, make sure you drive around with a glovebox full of deodorant and extra T-shirts. And plan on driving alone a lot.
So, the bottom line is: You’re right, Mike. At highway speed, they’re lowering their mileage with the windows open by reducing the car’s aerodynamic efficiency.
Maybe you can get them to compromise and keep the windows closed on the highway and let them lower the windows around town, where aerodynamics makes little to no difference.
Or, just accept the reality of the situation: There are two of them and one of you. Good luck, brother.
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