Video below shows the X5 M from the inside while driven on the Nürburgring. In addition, the tester talks about how BMW's M division is working on toughing this thing up. However, he didn't talk about the engine.
But reporters suggest that power will very likely come from either a 5.0L V10 with 507hp (found in the M5 and M6) or a 4.4L TwinTurbo V8 with around 400hp, found in the X6 xDrive50i.
When the X5 M comes out, it'll compete with high-performance luxury SUVs such as Porsche's Cayenne GTS, and Mercedes ML63 AMG. To make things even more challenging for competitors, BMW will also be releasing a X6 M along with the X5 M.
No word yet on when -and if- the BMW X5 M will find its way into production, but we expect to hit the roads in mid 2009.
Source : [BMW]