What is the optimal engine speed for a car?

[VonGabriel]

Engine operation is most economical and performs best when maintained within the range of 2200~3500r/min. It is advisable to keep the engine speed within this range during regular driving. Additional information regarding engine speed is as follows: 1. During cold starts, if the engine idle speed is below 800r/min or above 1200r/min, it indicates poor engine performance. 2. While driving, try to avoid operating the engine below 2000r/min, as low speeds can lead to insufficient engine power and excessive load, which can cause damage and promote carbon buildup. 3. When the engine operates above 4000r/min, the combustion time shortens, resulting in incomplete fuel combustion and a significant increase in fuel consumption. If driving in fifth gear at this speed, the vehicle typically reaches around 150km/h, which is already a dangerously high speed.