This is clearly not a mule. The body is practically complete and uses only very few parts from existing models. Many crucial elements are new, I'm actually surprised how little cladding there is in some areas.
@Jimmy and others already pointed out interesting design elements. What will change immensely from W222 to W223 is proportion and stance (imo, mostly due to changes in basic lighting units layout and c-pillar). And maybe, Daimler has the balls to introduce really new kinds of doorhandles.
Clinics have already been taking place a while ago, as far as I know. Where is the leak?
Seriously, that was a disaster back then.