What does "rev matching" involve?

Rev matching involves synchronizing engine speed with wheel speed to facilitate smoother gear shifts during a manual transmission operation. This technique is particularly important when downshifting, where it helps to ensure that the engine speed (RPM) aligns closely with the speed of the wheels and the gear being selected. By matching these speeds, unnecessary strain on the gearbox is minimized, and the risk of jerky motions or engine stalling is reduced, resulting in a smoother transition.

While other options mention aspects related to engine performance or shifting, they do not accurately capture the essence of rev matching. Increasing engine temperature before engaging the clutch is not relevant to the technique and doesn’t contribute to smoother shifts. Matching fuel flow to horsepower output focuses on a different aspect of engine operation and doesn't pertain to the mechanics of shifting gears. Reducing speed while downshifting may be part of the process, but it does not encompass the core activity of rev matching, which specifically centers on synchronizing engine RPM and wheel speed.