SMK, I am again going to explain you the reasons why the HF V-6 replaced the pushrod V-6.
1. HF engines are based on similar DOHC 4-cylinders which were developed for the Eco-tec engine family, not the V-8 push rods. It is easier and more economical to perform the economy of scales for V-6 based on the 4-cylinders, since those are engines shared in ALL GM brands and not only restricted to GM brands in America.
2. Because of displacement tax levied by many Asian and European countries, DOHC engines are used in light vehciles, as Dwight mentioned, NOT because they are more refined. So if I have to shell money for higher displacement, I will go for a lesser displacement engine producing similar performance, even if it means it is less refined than a higher displacement engine making similar power numbers and has a better feel to it. That is the main reason why Asian, European manufacturers have stuck with the DOHC's not because they are refined. The market demanded smaller displacement engines not refinement. Modern rules are now basing taxes on the emissions, but the old rules of taxing the displacement still persist in many countries.
As for the Pushrod V-8,
No other light auto manufacturer in the world other than American manufacturers sells enough volume of V8 engines to justify separate design and development cost for a V8 and be viable. Most of the V-8's sold by the luxury auto manufacturers are in America. In Europe and other countries they still sell majority of puny V-6 for their flagship cars. I will dare to say this the combined light vehicle V8's sold all over the world except America by all manufacturers will not exceed the V-8's sold by GM, Ford and Chrysler in their cars and pickup trucks. Barring luxury auto manufacturers and except for Hyundai and Toyota, which other manufacturers from Europe and Asia have a full fledged V8 serving in their light vehicles? Your highly acclaimed Tau engine is nothing but a big bored version with two extra cylinders of the 3.3L Lambda engine, so no Hyundai did not develop the engine from scratch.
As for the fitting of V8 in BMW and Merc sedans, let us fit a pushrod engine with higher displacement in the same engine bay and then compare which one will leave more space below those hoods. I have seen a 5.7L LS1 in a Honda S2000 without significant modifications. So yeah, pushrod packaging is comparable with a 4-cylinder OHC. :rollseyes: