In 2005, when BMW joined General Motors and DaimlerChrysler in a collaboration to develop hybrid technology, it seemed like a strange partnership. The two American companies were working on hybrids for heavyweights—a technology that could provide better fuel efficiency on three-ton full-size SUVs designed to carry seven or eight passengers, extra cargo, and tons of extra weight towed in back.

BMW’s Burkhard Göschel promised, “The technologies will be adapted to the individual vehicle models.” He said, “The participating brands will retain their distinctive characters.” The BMW Concept X6 ActiveHybrid, unveiled at the 2007 Frankfurt auto show, gives shape to the company’s distinctive interpretation of the full-hybrid technology.

The BMW X6 is a cross-over SUV that has crossed over into sports car territory. The company calls the vehicle a “sport activity coupe.” Its chief characteristics are a sleek profile, sloping roof line, low-slung stance, short front overhang, long rear overhang, long wheelbase, muscular wheel arches, large wheels, four-wheel drive, stability control, and lots of performance. And it’s the world’s most powerful gas-electric vehicle.

The drive system consists of a 400 horsepower twin-turbocharged V8 gasoline engine and two electric synchronous motors delivering 91 hp and 86 hp, respectively. Maximum system output is 480 hp. Interaction of the three power units optimizes the overall efficiency of the BMW ActiveHybrid X6 at all speeds, with acceleration from a standstill to 60 mph in 5.4 seconds. Top speed of the BMW ActiveHybrid X6 is limited electronically to 130 mph.

The two-mode full hybrid—which appears in American form as the Chevy Tahoe and GMC Yukon, and the discontinued hemi-powered Chrysler Aspen and Dodge Durango—has been BMW-ized in the X6 hybrid. The two-mode’s motors, batteries, gearsets and sophisticated software add up to a 20 percent fuel efficiency improvement over the conventional X6.

When we spoke with Tom Purves, chairman and CEO for BMW of North America, at the Detroit Auto Show, he said “A BMW customer may not be desperately worried about paying his gasoline bill. But he would like to have bragging rights that his new 7 series doesn’t just go fast, it actually uses a bit less fuel.” The BMW X6 ActiveHybrid is another example of how the company is keeping its focus on luxury and performance, while integrating slow steady fuel efficiency improvements which, by the way, come with the package. It’s a BMW first, and a hybrid second.