hoffmeister_fan
Kraftwagen König
MB always keeps development time lines for powertrain and new vehicles separate. They are very reluctant to deal with both engine and product change at the same time, and with most exceptions have sticked to that dogma.
For a time, the S-class usually would introduce powertrain architecture when a new generation S-class debuts and it would trickle its way down to other "lesser" M-B's during their mid-life cycle. Now, it's not like that so much.