Efficiency, yes. The second part is a little misguided though. The different gears in a transmission allow the vehicle to move at your desired speed while keeping the engine’s speed low, thus reducing fuel consumption.
Power to fuel consumption isn’t really a thing afaik. Naturally, a slower spinning engine will use less fuel.
One part is that a higher frame rate has less latency. At 30fps, every frame comes in around 33ms. At 165fps, that delay is reduced to roughly 6ms.
The other simple answer is just the advantage of more visual data over time.
TLDR: I like it when the game’s motion is smooth