What is the primary function of the starter motor in a vehicle?

The primary function of the starter motor is to turn the engine over. When you turn the ignition key or push the start button in your vehicle, the starter motor engages with the engine's flywheel and spins it. This action is essential because it initiates the process of combustion within the engine cylinders. Once the engine is rotating, the internal components can start the process of drawing in air and fuel, igniting it, and eventually producing power to move the vehicle.

In contrast, other options focus on different functions. For instance, storing electricity is performed by the battery, while the role of allowing the car to be started only when it is in neutral or park pertains to the safety interlock feature in automatic transmissions. Additionally, distributing voltage to the spark plugs is the role of the ignition system. Thus, the starter motor's unique function of turning the engine over is critical to the overall operation of the vehicle.