A motor for your motor, the BMW Starter is what you call on every morning to wake up your car. The BMW starter is a twelve-volt, high-torque electric motor with a special drive pinion. The drive pinion allows it to engage your flywheel ring gear, spinning the engine, then disengage from the ring gear once the engine is running. You’ve heard this drive pinion strike the ring gear if you’ve ever cranked your BMW starter while the engine was already running.

It takes a lot of juice to turn your starter motor, and that juice is supplied by the battery. In cold weather, the battery doesn’t produce as much electricity and the BMW starter is called upon to crank a motor with thick, cold oil inside it. As a result, you’ve heard the slow, laborious turning of the starter motor—hopefully followed by your engine firing up successfully.