Just got in from my day. Drove the 330d first and to be quite honest, I don't think I want one anymore. The extra power I thought it would offer, just didn't seem to be there?? Don't get me wrong, it was quicker than my 320d, just not as quick as I imagined. I don't know if it was the automatic that took the edge off though so would need to drive a manual.
Had a look round a 320si and thought that the trim was cheap, kind of like a crosshatched plastic. The surround for the start button also has some writing on it "limited edition" etc which I thought was a bit tacky.
The 535 next and a nice car although not as well laid out as the E90. by this I mean the position of controls /stop/start etc. It seemed big when I first got into it but I soon forgot about it on the twisty N.Yorks backroads. This was also an automatic but it suited the car better than the e90 auto.
And finally, a 2l Z4 - really good fun (sports suspension on 18's, manual) Quite a harsh ride but fun, fun , fun. I would definately buy a Z4 if I didn't need the 4 seats. I'd forgot how to drive a petrol though and it seemed weird at first to rev the nuts off it. This was needed though because it was slooow under 4k.
I hope I have not offended anyone with a 320si or 330d as this is not my intention, just my opinion.