Green cars from the Frankfurt Motor Show

At the Frankfurt Motor Show on Tuesday, BMW unveiled its new coupe-shaped X6 SUV. Alongside it, there was the ActiveHybrid concept version.

BMW touts the ActiveHybrid's responsive handling as well as its 20 percent improvement in fuel economy over a similar non-hybrid SUV.

The ActiveHybrid uses a version of the two-mode hybrid system developed by BMW in partnership with General Motors and DaimlerChrysler. Versions of that system will also be used on GM's Chevrolet Tahoe and GMC Yukon hybrid SUVs and Chrysler's Dodge Durango SUVs.

The two-mode system is engineered to provide optimal efficiency in both city and highway driving.