Official BMW X6 M Video Confirms Production Version, Power to come from Twin-Turbo V8
Up until now, the most powerful variants of the X5 and X6 models are equipped with BMW's new 408HP 4.4-liter twin-turbocharged V8 engine, something that leads us to believe that the 'M' variant of the V8 will deliver an output well over the 500HP mark. Our sources state that BMW will also use this engine on the next generation M5 and M6 models.