There are currently two kinds of Hybrid vehicle on the road: (a) those designed from the ground up with maximum fuel efficiency as their guiding principal, and  (b) working vehicles such as trucks, often based on pre-existing platforms, which have been given just enough hybrid capability to increase mileage somewhat while not degrading functionality.

BMW will be introducing a new, third type at the upcoming Frankfurt auto show: the high-performance, sport hybrid.  Named the ActiveHybrid X6, it will be the fastest and most powerful  gas-electric vehicle ever mass produced, with a zero to sixty time of 5.4 seconds, top speed electronically limited to 130 MPH, and 480 Horsepower available from its twin electric motors and 4.4L V-8 engine combined.  Fuel efficiency is improved 20 percent over the base model on the EU test cycle.  EPA figures have not yet been determined, but expect combined mileage to jump from the 15 MPG of the non-hybrid X6 to around 18 MPG when the hybrid is tested in the U.S. in the fall.