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Old 11-20-2012, 01:10 PM   #84 (permalink)
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Originally Posted by TheIVJackal View Post
Assuming we want the car to get up to temperature as fast as possible, what would be more beneficial? Which heats up the car faster?
Idling will heat it up faster - as the engine would still get some fuel to burn.
If you "coast in gear" i.e. use engine braking, there's no fuel going into the engine - provided you don't have an ancient car

As PaleMelanesian already wrote, it's best (for fuel economy) to keep the engine as cold as possible.

I coast in neutral with the engine on - as Hägar can't be bump started.
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