Bluetooth is a no-brainer. I wonder if OnStar will make that impossible.
Overall, I think just refining the feel and look would help a lot. The turn signal for instance. It just sounds cheap. The levers could have a more refined feel to them as well. I expect MP3 would be popular also. Push-button start and race-type flip switches instead of buttons?
On the look, the brushed aluminium doesn't look racy, it looks like plastic. There's far too much dash board out there, maybe break it up with some carbon fibre inserts or something. Hey, would it kill them to have some storage in that huge space?
Just my $0.02 worth!