Official M5 engine specs

Redline at 8.250 rpm
Maximum output 507 hp (373 kW) at 7.750 rpm
Peak torque 520 Nm at 6100 rpm
450 Nm available from 3.500 rpm
80% of maximum torque is available at up to 5.500 rpm

Engine weight is 240 kg, which is about the same the old V8 was.

Engine has "semi-dry sump oil system" which incorporates two oil sumps: a smaller one in front of the crossmember and bigger one behind.

The third generation SMG system is claimed to be 20% faster than SMG II

torque diagram:
http://www.bm3w.co.uk/ug/data/500/34graph.jpg
Engine:
http://www.bm3w.co.uk/ug/data/500/34engine1.jpg
also a new engine:
630Ci will have a new VALVETRONIC 3 litre inline six engine, with max output of 190kW(258bhp) and 300Nm.