I just had my Auto trans in the 300CD flushed replaced the filter and fluid with Mobil 1 Synthetic ATF.
My first impression as soon as I drove off was that.. the shifting was very very smooth. Sure enough it's a weird transmission and I could pick out a shift or two that I can actually feel. However it's a lot smoother and I guess it's just keeping up with the maintenance.
It could've been the filter and fluid though. However the ATF looked pretty clean before the change even.
2008 BMW 335i Coupe