Maybe only relevant in Australia, but models with a build date from September 2005 are distinguished differently from ealier models as having the 'MY06 Upgrade'.
One dealer here told me the difference between the two was that the MY06, had as standard several things that were options on older cars. These included:
Harmon Kardon Stereo
Folding side mirrors
Luxury seats
+ some other things
The guy didn't seem that confident or sure so I was hoping someone could spell it out for me.
Folding mirrors are not a U.S. option at all. The differences are the '06 has a quicker ratio steering rack, and an improved cluth pack on the supercharger. That's the only thing I know of that's changed on U.S. models.
This has been very helpful
I am trying to decide which year I should buy, the improved clutch - does that just make it smoother? I read on one of these forms that it stops it from doing some sort of infamous chirp - can someone elaborate more?
Yes, the updated clutch pack is meant to prevent, or cure the "chirp" on the older models and can be fitted to earlier cars (hopefully under warranty). The engagement of the clutch isn't all that smooth even on my '06. It depends on engine load and throttle position. It is sometimes very noticeable and feels like a slight stumble or hesitation. Other times you can barely tell. A higher boost pulley will make it worse.
Difference between '05 E55 and an '05 E55 with the MY06 upgrade 
Thanks 
Linear Mode
