Toyota Corolla heater: how does it work?

[Pannett]

The Corolla app allows the car to be pre-heated before a journey, so is there an electric heating system plus a heat exchanger from the coolant when the car is being driven? It's a very efficient system, but in the very cold current weather I direct the heat onto the face vents, which provide warmth very quickly, although the engine temperature gauge also rises to normal quickly too. So is it a hybrid heating system?

[Don Mac]

I think that there is an electric heater to supplement the heat from the engine.

But

If you use the pre-heating feature on the app the engine will run if the car decides it's necessary - this is why you get a warning about only using it where allowed (it's illegal in the UK to run the engine in an unattended car on a public road).