Another thread on making the US 325i into a 330 got me started on this. I was curious as to the transmission differences between the 2. They do indeed use different transmissions. But, I was curious to see what BMW did w/ the e60. Very interesting.

When the e60s had M54 engines, the 525i and 530i shared the same manual trans. But, when they swithced to the N52, the 530 kept this same trans, but the 525i got a different one (same as the e90 325i's):

http://www.realoem.com/bmw/partgrp.d...64&hg=23&fg=05
http://www.realoem.com/bmw/showparts...18&hg=23&fg=05

So, it looks like BMW felt the need to spec out a weaker manual trans with the engine switch as some sort of deterrent against making the "2.5" into a "3.0". Or, maybe they just wanted to save a few more pennies. Pretty cheesy, eh?