What should be done with the gear when parking a manual transmission vehicle on a downgrade?

When parking a manual transmission vehicle on a downgrade, it is crucial to engage the gear that will prevent the vehicle from rolling. Placing the gear in reverse (R) is the correct action as it utilizes the engine's compression and gearing to hold the vehicle in place. This helps to prevent any unintended rolling downhill.

In a manual transmission, engaging reverse ensures that the vehicle is less likely to move. The design of the reverse gear creates a mechanical resistance that works against the vehicle rolling down an incline. This is a critical safety measure to take when parking on a hill.

Options that suggest putting the gear in neutral (N), park (P), or drive (D) do not provide the same level of security on a downgrade. In neutral, the vehicle is entirely disengaged from the engine, making it vulnerable to rolling. Parking is not applicable to manual vehicles as it is specifically for automatic transmissions, and drive would cause the vehicle to move forward if inadvertently engaged. Thus, placing the gear in reverse when parking on a downgrade is the safest and most effective choice.