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As much of the United States struggles through the end of the nasty cold spell, a thought came to mind: Is it generally energy efficient to run the heat in my car?

Let me be a little more specific. I own a Chevrolet HHR, and as far as my understanding goes, heat is provided to the cabin by means of circulating part of the coolant loop near the blower when it is demanded (this much I think I know when I had to replace the heater core due to a mysterious coolant drainage).

Now, excluding the need for electricity being provided to the blower, am I essentially being energy efficient by using the engine's heat to stay warm instead of wearing my coat in the car, or is there a separate heating element that is using more energy?

gcode
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2 Answers2

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You are correct that the only extra energy consumed is the electricity used by the blower fan to move the warmed air. In the grand scheme of things the extra fuel required to generate that electricity is miniscule. The coolant is circulated regardless of the heater setting. Moving the selector to cool or warm merely directs all the air over the heater core or blends outside air.

mikes
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Here's a nice tip: if you turn up the heat in your car, it helps lower the operating temperature of your engine. Sometimes by as much as 10%. Not a problem when you're driving around in icy cold weather, but if your car is overheating, turning on the heat, opening the windows and putting the blower on full could save your engine from popping a gasket.

If you turn up the heat and it lowers your engine temp to within optimal temperature range, I would argue that it actually improves economy. But that's just theory. But as others have said, the theoretical difference in fuel consumption is too small to measure.

Captain Kenpachi
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