OK, made a mistake. That said, check out these lap times. The R8 is usually on more aggressive tires than the GT-S and has way more power (503 vs 610.) And, well, the SLS BS was actually very quick for how old it is now.

 

  AMG GT S SLS AMG Black Series R8 V10 Plus
Autozeitung test track 1:34.90 1:33.30 1:33.20
Motortrend Figure-8 0:23.20 0:23.10 0:23.20
Top Gear Track 1:17.50 1:19.00 1:15.70
Hockenheim Short 1:09.60 1:08.20 1:09.00
Sachsenring 1:35.25 1:33.38 1:33.78
Nürburgring Nordschleife 7:33.04 7:25.67 7:32.00