What is the reason for the RPM not dropping after releasing the accelerator?

[RachelMarie]

When driving at high speeds with engine load, releasing the accelerator does not immediately cause the engine RPM to drop. Instead, the RPM decreases as the vehicle speed reduces. This occurs because although the engine's fuel intake is reduced, the high-speed inertia of the car continues to "drive" the engine rotation, making the RPM proportional to the real-time vehicle speed. Below is an introduction to engine RPM: 1. The level of engine RPM affects the number of work cycles per unit time or the effective power output of the engine, meaning the effective power varies with RPM. Therefore, when specifying the effective power of an engine, the corresponding RPM must also be indicated. 2. The effective power and corresponding RPM specified on the engine's product label are referred to as the rated power and rated RPM, respectively. The operating condition of the engine at rated power and RPM is called the rated condition. Rated power is not the maximum power the engine can produce; it is the maximum usable limit of effective power determined based on the engine's intended application.