Stop-start engines function by shutting off a gasoline engine when the car is at rest, such as being stopped at a traffic light. The engine is then restarted automatically when the driver pushes down on the gas pedal.
These engines have already been placed in BMW's four-cylinder 1-series and 3-series models, which are not yet available in the U.S. It is believed that the six-cylinder 3-series will be the first of its I-6 models to get the new technology. It was announced, however, that all of BMW's I-6 models will eventually get the technology.
BMW is also planning to increase the production of four-cylinder models, which will be sold in the United States in the near future.
Source: 4CAR