What is the ideal RPM for driving at 120 km/h on the highway?
2 Answers
For family cars, maintaining an engine speed between 2500 RPM and 3500 RPM is generally considered reasonable. Here are some relevant details: 1. Manual Transmission: Generally speaking, at the same speed, vehicles equipped with manual transmissions tend to operate at slightly higher RPMs compared to their automatic transmission counterparts of the same model. 2. Function: The more gears a transmission has, the closer the gear ratios are, or in the case of continuously variable transmissions (CVT), the transmission can better match the engine's power output. This helps keep the engine speed within a relatively low range, which can reduce engine load and improve fuel efficiency to some extent.
When driving at 120 km/h on the highway, I find it most comfortable to keep the RPM between 2200 and 2600. My automatic transmission sedan is a 6-speed, and during normal cruising, it stays steady around 2300 RPM, with smooth engine sound and economical fuel consumption. If the RPM drops too low, it might cause vibrations—for example, dropping to 1900 RPM makes the engine run less smoothly. On the other hand, if it’s too high, it consumes more fuel, and exceeding 2800 RPM increases noise levels. Different vehicles may vary slightly—for instance, compact cars or SUVs might require slightly higher RPMs—but overall, this range ensures a comfortable and reliable drive. I recommend regular vehicle maintenance checks, such as transmission fluid and engine condition, to ensure safe travels.
