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The BMW X6 has always been a strange one. Not quite a car, or an SUV, and definitely not a truck, the sporty hard hat on wheels is a vehicular hybrid that could make the parents of a platypus proud. And now it’s available as…a hybrid, but not a typical one.

The 2010 X6 ActiveHybrid is the quickest hybrid in the world. It’s also the least fuel efficient. As with conventional engines, these things tend to go hand in hand.

The drivetrain combines a twin-turbocharged 4.4-liter V8 engine with two electric motors coupled to a 7-speed automatic transmission, and sends a total output of 480 hp and 575 lb-ft of torque to all four wheels. That’s a mighty amount of power, even in a nickel metal hydride battery-laden vehicle that weighs over 5700 pounds, a quarter-ton more than an X6 without all of the electronic goodies stuffed under that big hump in the hood.

The hybrid system is two-mode, so the X6 can cruise around on just the electric motors for short distances at low speeds – BMW says up to 37 mph - before the internal combustion engine comes to life. Driven with a light touch, the V8 usually lights up at around 20 mph, but you wouldn’t know it unless you were looking at the tachometer. The ignition is so smooth and quiet that the transition is absolutely seamless and better than any other hybrid on the road. Less so the other way around.

Lift off of the throttle and those motors start regenerating electricity so aggressively that they slow the car forcefully before you even step on the middle pedal. Some hybrids, like the Lexus HS250h, allow you to adjust this effect to a less intrusive, though less efficient level, but the X6 does not. When you do hit the brakes to come to a complete stop your sole is met with a spongy pedal, and the transition from regeneration to calipers squeezing disks about midway down is noticeable. You quickly get used to it, but this is a demon that most other hybrids exorcized long ago.

The accelerator is the more interesting place to put your foot, anyway. The X6 is absurdly quick for a green machine, and always ready to get out of its own and everyone else’s way. BMW says it can accelerate from 0-60 mph in 5.4 seconds. Even with all of the added bulk, it handles well, too. The street-focused, rear-biased all-wheel-drive system helps the not-so-tall crossover to approximate the responses of a sports sedan. The ride is supple on all paved surfaces – cobblestones included – and only let down by 20-inch wheels with fat, run-flat performance tires that can be harsh over sharp bumps. Don’t even think about taking them off-road.

When the X6 was introduced, BMW invented the Sports Activity Coupe moniker to describe it, owing to its low roofline and associated loss of some utility. But it’s not as bad as you’d think. Yes, there are only two rear seats, but they are darn comfy, and the roof is scalloped enough that six-plus-footers fit fine, though NBA starters other than Nate Robinson will still want to call shotgun. It’s the same story in the cargo bay where that sloping hatchback takes a couple of cubic feet out of the high side of the equation, but the cargo bay is long and wide enough to support four passengers’ worth of supplies and the back seats fold down to expand it even further for long, two-person road trips – but not too long.

The X6 wasn’t created to be BMW’s answer to the Toyota Prius. The EPA fuel economy rating is 17 mpg city, 19 mpg highway – call it 18 mpg combined. It’s unlikely that you’ll meet any environmentalists that will cheer that number, but it is 20 percent more than the lighter, less-powerful, but similarly quick non-hybrid X6 xDrive 50i can deliver. And that's the point: maintaining a desired level of performance while increasing efficiency. But, as is always the case with hybrids, it comes with a price. $89,775 to be exact, which is a whopping $21,950 more than the base price of the X6 xDrive 50i, but that's not the fairest comparison.

The X6 ActiveHybrid comes almost fully-loaded with everything from a comprehensive infotainment system to a head's-up display projected onto the windshield and cameras mounted around the car that give you a virtual bird's eye view of your surroundings to help out when parking. Load up an X6 50i with all of the same, and the difference shrinks to just a couple of grand. You still won't make it up at the pump anytime soon, but be patient, you may have just purchased a future classic.

The core mechanical technology behind the hybrid X6's was developed years ago through a joint venture between BMW, Daimler (then parent company of both Mercedes-Benz and Chrysler) and General Motors. The group has since broken up. BMW and Mercedes-Benz have moved on to an even more advanced lithium-ion battery-based hybrid system that is currently used in the top of the line full-size sedans of each company, and will be filtering throughout their lineups in the coming years.

So, as many believe the platypus to be, X6 ActiveHybrid may turn out to be an evolutionary dead end. But, like this odd BMW, those furry, duck-billed, egg-laying mammals are still pretty cool.

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2010 BMW X6 ActiveHybrid

Base Price: $89,725

As Tested: $92,275

Type: 4-passenger, all-wheel-drive 5-door crossover

Powertrain: 4.4L twin-turbocharged V8 with two electric motors

Power: 480 hp, 575 lb-ft torque

Transmission: 7-speed automatic

MPG: 17 city/19 hwy