Maybe you know GRIP, a german TV-Show about cars!
There's a recent thread here about their lap in a M5 at Yas Marina circuit! But they were at Abu Dhabi, and also on a drag strip, and there was also a 1M, rumoured to have500 HP!
The whole vid is worth to see, tuned X6M, 300 km/h on the highway etc, but the 1M can be seen at 12:40 and later on the drag strip, but unfortunately no more details about it!! Vid is in german only!!