Unlike the mainstream market where hybrid technology is used to maximize fuel efficiency, luxury automakers have employed hybrid systems as a way to maintain or improve performance while making concessions to efficiency. The 2010 BMW ActiveHybrid X6, which our testers got to drive this past weekend, is a prime example.

Based on the regular X6 "Sports Activity Coupe," which itself is a car of contradictions, the 2010 ActiveHybrid X6 is the first hybrid from the maker of ultimate driving machines and is due for retail sale next month. Oh, and it costs ninety grand.

Rated at a combined output of 478 horsepower and 575 pound-feet of torque, the big SUV uses a twin-turbocharged 4.4-liter V-8 engine and a nickel-metal hydride hybrid battery pack to claim the title of the world's most powerful gasoline-electric hybrid passenger vehicle. That's no mean feat, with contenders like Mercedes-Benz, Lexus and Cadillac in the space. The two electric synchronous motors contribute 91 horsepower/192 pound-feet and 86 horsepower/206 pound-feet, respectively.

This hybrid system is the same Two-Mode Hybrid architecture found in the full-size 2010 Chevrolet Silverado Hybrid and GMC Sierra Hybrid pickup trucks, as well as various full-size sport utilities including the luxurious Cadillac Escalade Platinum Hybrid.

But BMW has completely rethought the concept of "hybrid," using the software that manages all the electric components to mimic the driving behavior of a seven-speed automatic transmission.

Our testers drove the 2010 BMW ActiveHybrid X6 this past weekend at the international press launch, and aside from a few badges and the instrumentation, you'd never know it was a hybrid.

One thing that you will definitely notice is the gas mileage: EPA ratings for the 2010 ActiveHybrid X6 are 17 mpg in the city and 19 mpg on the highway, against the standard X6 xDrive 50i that uses the same twin-turbo V8, which delivers only 13 mpg in the city and 18 mpg on the highway.

The ActiveHybrid even has a better combined rating than the six-cylinder X6 xDrive 35i. And over a 100-mile-plus test drive, our testers saw average mileage of 20.4 mpg. Not bad for a large all-wheel drive sport utility that weighs almost three tons.

Our sister site Green Car Reports has full driving impressions of the new 2010 BMW ActiveHybrid X6, which you can read here. Otherwise, check out our review of the regular 2009 BMW X6 range by clicking here.


Follow Motor Authority on Facebook, Twitter, and Google+.