Just wondering for example just because a car has a 2 litre engine, it doenst mean that 2 litre capacity is used 100% right? it depends on the a certain area of rpm (power band) where it can fit most air efficiently and hence more fuel right?

just curious for example a 4th gen prelude h22a would use less fuel driving at low revs (esp with its steep powerband) opposed to like an auto 1.8 litre 05 civic which we also have at home

thanks