Which statement about double-clutching and shifting is accurate?

The statement that you can use the tachometer to tell you when to shift is accurate because the tachometer provides crucial information about the engine's RPM (revolutions per minute). When shifting gears, particularly in manual transmissions, it is essential to shift at the appropriate RPM to ensure smooth operation and avoid over-revving the engine or lugging it. Drivers often have a specific optimal RPM range for their vehicle, where the engine is most efficient and responsive for shifting. Monitoring the tachometer helps drivers make informed decisions about when to execute a shift, leading to improved performance and lifespan of the vehicle's transmission.

The other statements regarding double-clutching do not hold true in the same way. For instance, double-clutching is a technique primarily used with manual transmissions, not limited to automatic ones, and is beneficial in various driving conditions, not just under heavy loads or specific road conditions.