I have a 2006 Honda Civic Hybird.
When I turn the heater on does it just redirect already-existing heat from the warm engine, or is there actually a separate heater unit that uses energy?

I'm asking because I read about someone who saves gas by never using the AC or the heater.
Someone else said that not using the AC makes sense, but that the heater uses no gas since the heat comes from the engine block.

Need fewer troops to support.
Drive a hybrid.
Best tank 71.65 MPG.

Before this car I spent two years learning hypermiling on my 2004 HCH1.

The heaters in our cars tap the engine coolant loop, normally waste heat. However, our vehicles are so efficient that in cold weather, the cabin heat can reduce the coolant temperature too much and the ICE will come on to keep the engine at 'operating temperature.' This extra fuel burn can sometimes be avoided by minimizing use of cabin heat.

Over in Prius_Technical_Stuff, we'd talked about using engine exhaust heat for other purposes including cabin heat. The air-cooled VWs used this technique.

Bob Wilson

Operation Iraqi Oil Freedom:

Automatic, stock, project car.

My other 1500 cc car:

Automatic, stock, backup car.
Free speech, dialog and knowledge thrives without the poison of SPAM.

A trick if you ever get an engine that is running hot is to turn on the heat and fan to full (this seems to happen in the summer month on older cars) to cool down the engine. I had to do this with my CRX HF in heavy traffic once. Something broke on the car which prevented the coolant from circulating properly.

The Prius also has electric heaters to "boost" heating.

Pearl is a
2007 Driftwood Pearl Prius
Package "B" (everything but leather, nav, and rear camera)