Following the upcoming introduction of BMW's
roadster, the Munich automaker is considering a second, smaller roadster called the Z2. If the Z2 is built, it will likely be derived from the 1-series and - unlike the more powerful Z4 - the smaller car would probably use a four cylinder engine. It's also being reported that the Z2 could get a hybrid
drivetrain. If it does, it would likely be the mild hybrid system that will debut in the new 7-series next summer. That system consists of a motor sandwiched between the engine and transmission along with a lithium ion battery. Such a combination might match the performance of the larger Z4 with significantly lowered fuel consumption.
[Source: BMW Blog