What is the ideal engine speed range to maintain?

[MacPenelope]

Engine speed is generally recommended to be maintained between 1000 and 3500 RPM, with peak torque output typically occurring around 3000 RPM, after which it becomes inversely proportional to speed. Higher engine speeds result in more work done per unit time, thus increasing power output. However, excessively high speeds accelerate the entire combustion cycle, causing fuel to be expelled before complete combustion occurs. Most vehicles achieve optimal fuel efficiency at speeds between 60 to 90 km/h. Both excessively high and low speeds negatively impact fuel economy - at low speeds, piston movement is too slow for complete combustion, while high speeds increase intake air velocity and consequently intake resistance.