BMW ActiveHybrid 5 preview (photos)

The gasoline engine is BMW's tried and true twin-scroll turbo direct injection 3-liter straight six. By itself, it is more than adequate for the 5-series, producing 306 horsepower. But the hybrid system adds both power and fuel economy, efficiency gains that are hard to argue with. In addition, the hybrid system lets the car drive in electric mode, useful for stop-and-go traffic or urban zones that only allow electric vehicle operation.