As much as I hate all of this, that engine is impressive.
Tri-turbo 3.0L i6 making 381hp@4400rpm with 5400rpm redline, 546lb-ft torque @ 2,000rpm (albeit ending at 3,000rpm). So it's peaky but interesting for an everyday vehicle.
550d sedan does a 4.7s run to 100. That is on-par with the M3.
///M Power - 2011.75 LMB M3 6MT (fuelly)