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.

[–] [email protected] 5 points 1 year ago* (last edited 1 year ago)

Sorry for unclear wording, I meant that you obviously need some level of power output to move, but you need different levels of power output to keep moving at any given speed, hence the gears. What I meant by 'power to fuel consumption' was that while you theoretically could go at a high speed using a low gear up to a point, that would be very inefficient. I'm not actually an engineer, though I pretend to be one at university.

Good thing I'm not an educator!