this year, we reported that BMW's normally aspirated inline-6 engines will
be ushered out and replaced by a new family of turbocharged four-cylinder
engines. BMW today
confirmed that four-cylinder power would return to U.S.-bound BMWs after a
10+ year absence.
The first model to get BMW's new 2.0-liter
TwinPower Turbo four-cylinder engine will be the Z4 sDrive28i Roadster (say
that five times fast). The engine develops 240 hp and 260 lb-ft of torque (30
percent more torque at 1,500 fewer RPMs than the naturally aspirated 3.0-liter
BMW says that the new turbo four will be 20
percent more fuel efficient than the inline-6 when paired with the 8-speed
automatic transmission. We're sure that there are fuel efficiency gains to be
made with the 6-speed manual transmission as well, but it's likely nowhere near
20 percent (or else BMW would have mentioned it in the press release).
The Z4 sDrive28i Roadster will arrive in showrooms this fall, and
the turbo four will likely filter down to other BMW models soon after.
quote: But this link claims that RON and PON, the American method, has basically the same octane rating.