The new V-8 is rated at 400 horses and 450 lb-ft of torque, making it the most powerful engine ever available in a BMW sport/ute, easily topping the X5's 350-horsepower, 4.8-liter naturally aspirated V-8. Engine torque reaches its peak at 1800 rpm and stays there until 4500 rpm, which makes the M3's rev-happy V-8 -- with its 295 lb-ft of torque -- seem puny by comparison. BMW says the engine will propel the X6 from 0 to 60 in just 5.3 seconds -- an impressive number for a vehicle likely to weigh well over two tons and just 0.4 second slower than the 500-horsepower Porsche Cayenne Turbo. Top speed is electronically limited to 155 mph on 20-inch-wheel-equipped models
The X6 will come in two variants. The xDrive35i is powered by the now familiar 300-horse, 3.0-liter twin turbo inline-six. But the big stuff what's under the xDrive50i's hood -- a new to the BMW lineup 4.4-liter twin-turbo V-8. Both engine variants are mated to a six-speed automatic with paddle shifters, and as the names imply, come standard with BMW's xDrive all-wheel-drive system that sends 40 percent of the power to the front wheels and 60 percent to the rear under normal driving conditions
Like the twin-turbo inline-six, the new V-8 uses direction fuel injection and two small turbochargers, one for each cylinder bank. The turbo units are innovatively packaged along with catalytic converters in the center of the block between the two cylinder banks. This packaging means reduced pressure losses due to shorter intake and exhaust manifolds, improving engine efficiency. And as with the twin-turbo six, BMW has worked hard to use the setup to help eliminate turbo lag, which will be especially helpful on a vehicle as heavy as the X6.