There are many opinions and worries about BMW's direction with going turbocharged and how the last generation aren't "real" M cars anymore...
Thought this review by Chris Harris on the M6 GC vs Jag XF-R vs E63 AMG S was quite informative end entertaining
Shows that one more of the respected reviewers comment on how the S63TU engine in the M5/M6 is in a class of it's own. Hopefully the S55 will be even more special