Oh, ok, so your problem isn't with turbocharged engines, but with powerful engines. No argument here. I agree that an engine with less power is often more fuel efficient (speaking as a former owner of a 318i)

The article was proposing smaller turbo engines with the same power as larger naturally aspirated engines. The turbo models will be more efficient at the same power (as well as being lighter). Your 325 could then tie a 316 turbo in a race while consuming more fuel.

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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