Someone has probably mentioned these before, but I couldn't read all the posts here. After 1500 miles, these are my main ones:
Cache Google Maps! With Google Maps on my phone, I was able to drag a box around the SF bay area, and save the entire bay area on my phone for about 50 or 75mb. All my maps load instantly and never have to wait for anything to load. Makes the map app wonderful to use, and my friends commented on how super fast my phone was when they first saw it. The car's maps load so slow its kind of hard to use sometimes. Cached maps would solve that issue and provide a MUCH better user experience, and hopefully passengers would be impressed instead of commenting how slow it loads! Tethering my 4g lte phone would probably help (USB tether would be nice too!), but there is no reason to constantly download the data when you can cache it locally for such a small amount of storage.
I'd like to be able to switch media source by voice command. Play FM, USB, etc. (my brothers Ford Focus does this, poorly, but it does it) Voice commands to play local media, instead of just Slacker, would be great as well. Play Song by Artist from USB. A shuffle button for playing from USB would be cool too.
Expand voice commands -- open pano roof, set suspension height, etc.
Enable Flash/HTML5/Video when in park, so the web browser has a use instead of being a novelty.
Instrument cluster items:
Add a compass to the gauge cluster. Would also be nice to list the street you are currently on, even if not using nav.