The engine offer much power at a very high revolution range. (thekoreancarblog.com)
But, in hibernation, it has a lot bigger role in controlling body temperature, making the mitochondria a lot more active, the same as an engine that's running at high revolutions per minute while the clutch is uncoupled / disengaged. (fitnessandpower.com)
With variable - valve timing and direct injection, the engine works efficiently at high revolutions per minute, but at lower rpms it actually switches to a set of secondary port injectors to lessen engine noise. (cnet.com)