Why should you not apply the clutch when driving on a long, steep downhill slope?

When driving down a long, steep slope, applying the clutch can lead to several issues.

Firstly, disengaging the clutch removes the engine's braking effect, which can result in increased speed and reduced control over the vehicle. This braking action produced by the engine is crucial for maintaining a safe speed on descents.

Secondly, using the brakes excessively in this situation can lead to unnecessary wear and overheating of the brake system. In German traffic regulations, maintaining vehicle control and ensuring safety are paramount, which is why it's important to use engine braking when possible.

Lastly, while the third option regarding the brake servo unit is not correct in this context, it is important to understand that components like the brake servo depend on the engine running properly. However, it's the first two points that primarily explain why engaging the clutch is generally not advisable during steep descents.

In summary, using the engine for deceleration helps maintain control and minimizes brake wear, aligning with best driving practices and safety regulations in Germany.