BMW doesn't make their own transmissions, they buy them off the shelf from a company called ZF. ZF makes a multitude of transmissions for tractors to semi's to BMW's! BMW uses their own programming to run the transmission and control it's shifts.
The transmissions are different to an extent depending on your model. The 740's and 750's and B7 from 2009-2012 use the same transmission as the E65/66 from 2002-2008, the 6HP26Z from ZF. The X-drive models use a slightly modified version of the 6HP26 called the 6HP26Z-WHK
The Hybrid 7 uses a ZF transmission called the 8HP70H which is an 8 speed transmission with the hybrid motors and such inside. The 760 uses an 8HP90Z transmission which is an 8 speed, but it is built with better components to handle all the torque and power vs the hybrid.
As far as power ratings for the ZF trans goes heres what I found with a quick search:
8hp30 - 300nm (221 lb-ft)
8hp45 - 450nm (331 lb-ft)
6hp26 - 600nm (442 lb-ft)
8hp70 - 700nm (516 lb-ft)
8hp90 - 900nm (664 lb-ft)
Last edited by csmeance; 12-28-2012 at 04:30 PM.