Better standard fit stereo - I know there needs to be a reason to tick the options box for the premium stereo, but the standard E90 one is very very poor!
Better placement of aux-port and 12v/cig lighter. People often use aftermarket satnavs and like to have the ipod sat outside the armrest cubby hole.
Lose the auto-dimming rear view mirror, and just have a manual 'tilt' option instead. Is that a police-car behind me?! No idea thanks to the auto-dimming mirror