Does running the heat affect fuel efficiency?

We’ve all heard that air conditioning makes an impact on how much gas you burn, and sometimes that’s true. What about other accessories? With fall here, and winter soon on its heals, it’s time to look at how your heater and defrost impact your miles per gallon.

Does Running the Heater Affect Fuel Efficiency?

Realistically speaking, no. Most heaters work off of “waste” heat or heat coming off the engine. There is a small amount of electricity used for a blower but nothing that would place a significant drain on the auto.

Does Running Defrost Affect Fuel Efficiency?

Surprisingly (at least, for me) YES. The defrost setting, even when set to heat, uses the AC compressor which can have a noticeable impact on your fuel efficiency.

What if your windows are always fogging up? Make sure your heater is set to intake vs. recycle the air in your auto. If that doesn’t help, check the heater core to make sure there are no leaks, or anything blocking fluid from draining.