Off and on.

The Auto Start Stop function in the BMW 3 Series Sedan.

Red lights, traffic jams, road works - in everyday driving situations there are countless instances where the engine is idling, unnecessarily burning fuel. The Auto Start Stop function* is a system that automatically turns off the engine when it is not needed, and turns it on again when it is. This not only reduces fuel consumption, it also lowers emissions.

*In all four-cylinder models with manual transmission.