What is a true statement about double-clutching and shifting?

The correct statement emphasizes the use of the tachometer as a valuable tool for determining shift points in a vehicle. When driving a manual transmission vehicle, the tachometer displays the engine's RPM (revolutions per minute). It helps drivers know when to shift gears to maintain optimal engine performance and efficiency. Shifting at the appropriate RPM helps prevent engine strain and ensures smoother gear transitions.

Understanding how to read and interpret the tachometer is crucial, especially for maintaining the right balance of power and fuel efficiency. This is particularly important in commercial driving, where loads can be significant, and optimal performance is necessary for safety and efficiency.

In this context, the other statements do not accurately reflect best practices or common knowledge regarding double-clutching and shifting. For instance, double-clutching is a technique often used to ensure smoother gear changes, especially when downshifting, but it's valuable regardless of load or road conditions. The notion that shifting is unnecessary while driving downhill is misleading, as proper shifting can help control speed and maintain vehicle stability.