What are two main reasons coasting downhill is considered dangerous?

Coasting downhill is considered dangerous primarily because you have less braking control and the vehicle will pick up speed. When a vehicle is in neutral or the clutch is disengaged while descending a slope, the driver loses the ability to respond effectively to sudden changes in the road or traffic conditions. Without engine braking, the vehicle can gain speed rapidly, making it harder to control, especially if you need to stop suddenly or navigate around obstacles. This situation can lead to unsafe conditions not only for the driver but also for other road users.

The mechanics of coasting eliminate the natural resistance that the engine provides when it is in gear, which usually helps to slow down the vehicle. Therefore, maintaining control while driving downhill is critical for safety, and keeping the vehicle in gear allows the driver to utilize engine brakes, enhancing overall control and stability.