I’ll be the first to admit I could be wrong here as the N54/N55 changeover was murky. All I can say with “certainty” is that it happened sometime in 2010, and any 2011 model year BMW (barring the 335is) with a turbo I6 should be N55-powered. But, every now and then, I’ll hear of an 2010 E90 with an N55, though. Super…