First of all, the RS6 has Not been released yet.
Second, the fastest recorded M5 0-60 time was 3.78 seconds. So no the RS6 is NOT faster.
(If you really want to compare 0-60 time, tell me why the Nissan GTR with 530hp does 0-60 in 2.7?)
2011 535i Alpine White, Oyster on black interior, Premium 1 & 2 Package, Magnaflow Full Cat-Back Exhaust, JB4 Stage 2