In the week of 22-25 July 2014 we spied four prototypes of the all-new Mercedes-Benz C 63 AMG W205 undergoing testing on the Nürburgring Nordschleife. There were both sedans and an Estate being tested on the track. What caught our attention though is that the prototypes sound different compared to eachother. Check for instance the sound of the prototypes starting with an ‘A’ in the licenseplate, and the C63 Estate and sedan with ‘BB’ at the beginning of the license plate. Completely different sound. Perhaps the last two mentioned are testing in Sport+ mode, or maybe even better.. They might be testing a performance package for the new C63 AMG, or even the ‘S’ version as we’ve seen with the E63 AMG. What do you guys think?