system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Is it more efficient to put my car heat on 1 and let it heat my car slower or put in on full, 4, and heat my car faster?
gpt
Run it full blast: it's not like you're "conserving" the engine's heat by running the heater on low. 

Your car's heater runs off waste engine heat. When the motor burns gasoline, it gets hot, and so your car circulates coolant around the engine block and dumps the excess heat via a radiator behind the grill.

When you turn the heater on, a fan blows across a smaller, alternate radiator called the heater core, and the heated air comes out vents in the cabin. 

Go ahead and run it full blast--the engine produces *so much* heat that you literally cannot cool off the heater core while the engine is running. It takes a little while to warm up (ie, for the motor's heat to bring the coolant up to temp), but that little pissant heater core only dissipates a small fraction of the waste heat (most of which is shed through the primary radiator behind the grill).