F31 Engine details now up on BMW UK website and yes there is a 3.0l 6 cylinder engine available on the SE and MSport - 258 bhp, 560 Nm twin turbo delight. 0 to 62 in 5.6secs yet returning 55 mpg on the combined.
http://www.bmw.co.uk/bmwuk/pricesand...calSpec&isPGA=