BMW launched the 650i convertible this week to much fanfare. Hidden away was the inline six 640i, the less powerful and more efficient offering that will launch initially in only the EU market. There is no timetable on a North American launch but if the recent introduction of the 740i is any indicator, it will be at least a year before we see it in the US.

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 N54 performance with greater response and operating efficiency. The 640i receives around a 20 hp bump from yet unnamed improvements.

We also predict that other models will see this engine upgrade (Recall that 5 Series testing one of our readers spied) as always, when we hear more we will keep you informed.