Originally Posted by Autumn
The sport auto shifts more quickly as well.
Yep, sport auto shifts quicker (200ms), you get flappy paddles, a nice leather surround around the improved "gear stick" and slightly different software. For what it's worth (£150 difference in the UK) go for the Sport Auto. I drove a 328i with the standard auto and it wound me up because it had constant power interruptions and the lack of flappy's to control it was a hindrance. Therefore I feel the Sport Auto is smoother.
Oh and it adds the Sport + mode!