Today auto motor und sport has the test including the clk500.

The BIG surprise is the dynamic performance of the S5: clearly a cut above the bmw's, who we know is pretty good!
but even futher, in the so called 'ausweichstest' (thats the lane change) the car is superior to the RS4 and the Gallardo spyder!!
In slalom and ISO-wedeltest the performance is on par with the Porsche Turbo!!
They claim the dynamics of the car are excellent, the new engine/transmission layout has eliminated understeer, the brakes are excellent (feel and performance), the stering very good. It is also worth noting that the car was tested with the standard 18" wheels and not the 19" which would have further improved the results!
0-100 measured in 5.3, vs bmw 5.6
0-180 15.6 vs 16.9
Interestingly also the elasticity measures (like 80-120) are slightly better/on par with the bmw who is helped by the biturbos with 400nm at 1500revs already.

alltogether this car clearly delivers to it's great sound; and the m3 better be very good or the rs5 will trash it..