There will be no X5 M.

BMW are interested in offering X6 as an exclusive performance " off road " Ultimate Driving Machine in our model line , so we will offer the X6 M will with award winning V10 S85 engine under the hood.
Top-end V8 X5 version set above 4.8i will be offered after X6 is introduced in Spring 2008.
For those who really strive for performance oriented vehicle with high driving position I suggest to wait for X6. You'll be delighted!