I guess if people want the right to say they have a naturally aspirated engine. Bigger displacement wouldn't mean much to me. I think more people will care about the performance, and the turbo models will be far more desirable IMO.

See what happens to values of the last M5 when the new M5 blows it into the weeds with a smaller (turbo) engine with fewer cylinders.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue