The S54 engine in the E46 M3 has individual throttle bodies mounted near the injector. The whole intake plenum (there is no traditional manifold) is tuned to be an efficient air pump at extremely high RPMs (8000rpm red line). Newer BMWs like the 325i described by yahman don't have a throttle plate at all. They utilize gasoline direct injection in conjunction with infinitely variable intake valve lift and timing to eliminate all pumping losses. Because of the direct injection, these engines can also run ultra lean fuel mixture while cruising at constant speed without running into the NOx problems honda had with its VTECe engines. A lot of the traditional preconceptions about these cars no longer apply. Last winter I drove a BMW 335xi (4wd automatic twin turbo 300hp) while visiting relatives on the east coast. Over 2 weeks of stop light races and triple digit sprints I managed 23mpg. Not bad at all in the dead of winter with 4 people in the car.
More on direct injection.
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BMW N52 engine.
Inside the N52 Engine
