Greeting gents,
I found a YT video showing the difference in a drag race between the xDrive 50 and M60.
The race was not optimal (raining), and both car didn't do their best. The same channel previously tested the M60, and it did 0-62 mph (0-100 kph) in 3.59 against an X6M.
Regardless, it shows the difference in power. M60 has a larger and oil-cooled rear motor, and that's the contributing factor.
Both are very fast for a heavy SUV.
Enjoy.