What is the purpose of the parking or emergency brake in vehicles?

The primary purpose of the parking or emergency brake is to secure the vehicle when parked. This brake, often referred to as the handbrake or foot brake, is designed to keep the vehicle stationary, particularly on inclines or uneven surfaces. By applying the parking brake, drivers ensure that their vehicle does not roll away when parked, which is crucial for safety.

In contrast, the other options pertain to different functionalities that the parking brake does not serve. For example, while gradual stopping is typically managed by the regular braking system of the vehicle, the parking brake is not used for this purpose during normal driving. Fuel efficiency and speed control are also not roles assigned to the parking brake, as it does not influence the vehicle's performance while it is in motion. Thus, recognizing the parking brake's specific function is important for safe vehicle operation and understanding vehicle systems.