While the conventional X6 that's currently on-sale is powered by a 300-horsepower, twin-turbo inline six-cylinder engine or a 400-horsepower V8, the hybrid relies solely on a V8 with two electric motors attached.
The hybrid system on the X6 is described as a two-mode hybrid system -- a complex mechanism developed jointly by General Motors, BMW and Daimler. The system uses three gearsets in the transmission that split power between the gasoline engine and the two electric motors. The two electric motors are run by a large battery pack.
The transmission determines when the car should run on electric power, gasoline or a combination of the two. It's ideal for SUVs because of its ability to pull large amounts of weight, and has actually been used on GM transit buses for years [source: Stahl].
On the X6 ActiveHybrid, the two-mode system means just that: one transmission mode that uses the electric motors for maximum efficiency while pulling away from a stop and low-speed driving, plus a second mode that's ideal for high speeds and bursts of acceleration [source: BMW.com]. The brakes also capture kinetic energy during deceleration to recharge the battery pack.
The goal of this is to create what BMW calls "Efficient Dynamics," or a vehicle that is exhilarating to drive without sacrificing fuel economy. They hope to combine the best assets of electric and gasoline engines to create new levels of performance -- for example, taking advantage of the fact that electric motors hit their peak torque instantly from a standstill. With the gasoline engine providing power at higher speeds, a fast car is created that requires less fuel to achieve high performance [source: BMW.com].
All this technology is expected to increase the X6's fuel economy by up to 20 percent. While mile-per-gallon and horsepower figures haven't been released by BMW just yet, a 20 percent increase in fuel economy over the standard V8 would mean the BMW X6 ActiveHybrid could achieve nearly 22 miles per gallon (about 9.4 kilometers per liter) on the highway. That's a respectable figure for a car that weighs so much and puts an emphasis on spirited driving, as well.
As mentioned before, there are always tradeoffs involved. The ActiveHybrid system will add both weight and additional cost to the X6. However, the concept -- possibly set to be in production by 2010 -- shows that perhaps we can have vehicles that can do it all, from SUV capability to performance and even Earth-friendly emissions levels.
For more information about the BMW X6 ActiveHybrid and other hybrid car topics, follow the links on the next page.