I foresee a 100 page thread with lots of flames flying around
Maybe it can do that because it was developed to be a 4 door sports car from the beginning. The M5 and CTS-V are essentially normal saloons with jumped up hardware attached to them later.
Regarding the 430 and the SLR, both of them are getting on a bit now and the 'mera is only a few months old. Advances in technology surely played a part.