To control speed on steep downgrades, drivers should:

Using a lower gear when driving on steep downgrades is crucial because it allows the engine to help slow the vehicle down through engine braking. This method takes advantage of the engine's resistance to help maintain a safe speed without relying solely on the brakes, which can overheat and become less effective if used too aggressively. By shifting into a lower gear, drivers can keep their speed under control and prevent losing traction or control of the vehicle, making it an essential technique for safe driving on steep hills.

Other options, such as shifting to neutral, can lead to a loss of control over the vehicle, since the driver would be unable to use engine braking effectively. Accelerating slightly would only increase speed, which is dangerous on a downgrade. Engaging cruise control is not advisable as it can cause the vehicle to accelerate beyond a safe speed without the driver being prepared to respond to changes in incline or road conditions.