Why Downshift for Overtaking? Can't You Accelerate by Upshifting?
3 Answers
Gain more power. Here is the extended explanation: Principle: At the moment of downshifting, the engine speed immediately increases while the vehicle speed remains unchanged. As the transmission gear ratio increases, the torque output from the engine to the wheels also increases. After completing the downshift action, the car usually decelerates by reducing the throttle (so-called deceleration downshifting). With greater torque output, continuing to press the accelerator will result in a significant acceleration, causing the car to speed up rapidly. Reason: To obtain greater torque and increase acceleration. The speed of the car (including acceleration) is not directly related to the gear of the transmission.
Downshifting for overtaking allows for more aggressive acceleration, primarily because the engine delivers maximum torque in the higher RPM range. After years of driving manual transmissions, I've deeply experienced the benefits of downshifting: when the revs climb above 3,000 RPM, the engine feels like it's on adrenaline, unleashing full power to propel you past the car ahead in an instant. While upshifting also provides acceleration, it lowers the RPM, making the engine feel sluggish—like taking leisurely steps—resulting in slower response times. This is especially crucial when overtaking trucks on highways, where downshifting lets you complete the maneuver in seconds, minimizing time spent in dangerous positions. An added benefit is that it keeps the engine healthier by preventing carbon buildup caused by high load at low RPMs. Automatic transmission cars typically feature kickdown functionality, which operates on the same principle—ensuring a burst of power for safer and more efficient overtaking.
As a long-distance driver, I feel downshifting for overtaking is almost instinctive. The moment the engine revs up, the whole car instantly comes alive, with acceleration response as quick as an electric shock. In contrast, upshifting is like boiling a frog in warm water – it can increase speed but does so sluggishly, lacking the instant explosive power when needed. The advantage of downshifting is that it shortens overtaking time and reduces the sense of insecurity in narrow lanes. I've also noticed that, when combined with throttle adjustments, downshifting enhances driving smoothness, such as providing more stability when overtaking on curves. This level of control is something upshifting can't offer; it gives you more confidence in mastering the road.
