Slotted between the engine and PDK transaxle is a 156-hp motor that can propel the car, supplement the engine's power, and act as a generator while braking regen or even while accelerating when the engine is instructed to work even harder to restore the battery's state of charge.
If you get the chance, we always suggest a pre-purchase inspection and shakedown from a specialist, but given the typical light use and young age of 918s, there shouldn't be any nasty surprises—yet.
As well, only 918 units were made, making it a rare and ultra desirable beast.