Eventually the plan is to have the release just include 1 community-modeled car and 1 community-modeled track, and then provide a data-manager application to download more cars and tracks separately. I'm not sure if we'll get all of that done by the next release. As for the release timing, I have a post here:
http://vdrift.net/Forum/viewtopic.php?t=736
where I've made a list of things that I broke when re-writing the graphics engine. As you can see, they're almost all fixed again, so I think once that list is done (a few weeks) it'll be time to release, since there have been a ton of bug fixes and improvements since the 3/23 release. After that release, we can start getting to work on some of the polish:
http://wiki.vdrift.net/Release_Planning