You can read about the C63 AMG Black Series this week, but here is a spy photo of an even bigger bruiser from the German high-performance car maker: the 2013 Mercedes SLS AMG Black Series. Caught at a testing centre in Germany, the prototype has a wide body kit with a modified front fascia, revised side skirts and extended wings. We can also see high performance brakes and larger rear wheels, which hint at some changes to the rear axle. Under the bonnet, rumours suggest the 6.3L V8 engine could deliver 600hp and 677Nm of torque. This will likely enable the car to accelerate from 0 to 100kph in 3.5 seconds and hit a top speed in excess of 322kph.