Nordschleife: 8.32 min
Hockenheim: 1.17,8 min
0-100km/h: 6.0 sec
0-200km/h: 24.5 sec

Slalom 36m: 131 km/h
Slalom 110m:145km/h
Wet track: 1.34,2 min (same laptime as Zonda F)

Some qoutes

even though to the stiffer bodywork the Z3 3.0si coupe is not faster than the 3.0si roadster (tested a different day), the whole set-up, weight and areodynmic is more or less the same. The handling of the coupe still is superb, the brakes also can stand a few laps at the Nordschleife.
Beats the Opel Speedster Turbo to 2 secs., the Porsche 986 Boxster to 4 secs. and the Honda S2000 to 7 secs.

At the Hockenheim short track the coupe is 0.2 secs. quickerer than the roadster (tested a different day), here you can see the advantage of the coupe and the stiffer chassis.

at the 36m handling track the Z4 3.0si coupe shows its class: at 131 km/h it is asfast as a Lamborghini Gallardo, Ferrari F430, Mercedes SLK 55 AMG

145 km/h in the 110m evasion test is even a bit faster than the F430 and jsut a bit slower than the mighty Dodge Viper SRT-10, handling is jsut perfect

Verdict:
the Z4 3.0si Coupé with a MSRP about 50,000 EUR is no bargain but a true sports car woth all the money. It si comact and not so heavy and so it offers a lot of fun with the powerful and sporty 6-cylinder engine. There is no difference in handling compared to the Z4 roadster. It is just a question od heart or brain wether to take the roadster or coupe, BMW Motorsport ahs decided on the coupe as a basis for furjter race efforts.