da bimmerfile: -The 740i features a mildly tuned version of the N54 twin turbo motor and it’s EU launch foreshadowed a series of things, including tuning options from BMW Performance. With the recently announced (in the EU specifications) 640i BMW has shown us the first “tune” of the N55 engine. As you may already know, the N55 uses as single dual scroll turbo and BMW’s Valvetronic system to match the N54 performance with greater response and operating efficiency. The 640i receives around a 20 hp bump from yet unnamed improvements. As we get more details we will keep you informed.
