Mercedes has been caught testing its latest version of the C63 AMG at the famed Nürburgring. The short spy video depicts the V-8 brawler ripping around the track with Jaguars and BMWs all around. No doubt Mercedes is sizing up the competition. The performance sedan will be all-new for 2015, just as its less-powerful C-Class stablemates. With plenty of design cues coming from the ritzy S-Class, the C is quite the looker.