The whole process is more expensive ( from engine block casting, to crankshaft, etc ).

Ok, how so? Why? Looking for specifics here. For example, how is casting two heads cheaper than one?

As well as, a V - 6 engine can be machined on the same " line " as a V - 8 engine, which also streamlines the procedure.

The old sixes were the same as the 4 cylinder engines. Look at a 102 and a 103 motor. Same thing, different # of cylinders. Same for 104 and 111 motors. And 601/602/603 motors. And 616/617 motors. This modular design is NOT new.

__________________
'90 300SE 298k
-300K and it gets put into retirement.
'80 300D 255k Purchased new by family in 1980.

Had a:
1973 220 (gas)
1980 300SD
1992 400E