Which statement is true regarding double clutching and shifting?

The statement about using the tachometer to tell you when to shift is accurate because the tachometer displays the engine's RPM (revolutions per minute). Understanding how to read the tachometer allows a driver to determine the optimal shift points based on the engine's performance and power band. When the RPM reaches a certain level, shifting can occur to ensure the engine operates efficiently and effectively. This technique helps maintain the appropriate balance of power and fuel consumption.

The other statements do not hold true in the context of double clutching and shifting techniques. For instance, double clutching is employed primarily in manual transmissions, making the assertion regarding automatic transmissions incorrect. Additionally, while double clutching can be beneficial in certain scenarios, especially for smooth downshifts in manual vehicles, it is not strictly necessary for every driving situation. Finally, the claim that it should only be used during city driving fails to recognize that double clutching can also be relevant in other settings, such as when negotiating hills or performing maneuvers on highways.