So according to the BMW site, the M550i xDrive will have 462hp and can run 0-60 in 4 seconds flat. This makes it quicker than the current M5 thanks to xDrive, an increase in power, and probably lighter weight as well.
http://www.bmw.com/com/en/newvehicle...rformance.html
http://www.roadandtrack.com/new-cars...-acceleration/
I'm really glad BMW decided to step it up on the 550 so it can better compete against the S6, and actually made it distinguishable from the other G30's. Unlike our current F10 550's which you could only tell the difference by looking at the exhaust