This mod will provide you with extra courses to practice/race on. To clear any confusion, it doesn't add any new levels for AI races. All it adds is new tracks that can be found in sandbox mode. Keep in mind the mod is in a very early stage, for now it only adds one new course, which can be found at the Krakabloa islands.
THE MULTIPLAYER RACING LEAGUE
The multiplayer racing league wil be a series of events where multiple players race against each other online. There are several different classes of races each with their own rules. Events will be scheduled in a future forum post, where you can enter. The races are primarily for fun and will be held on the event server, or when that one's down the main server (220.127.116.11). For anyone interested, here is the original post.
While not necessarily required for participants, I advise you to get this mod so you know where to go during a race if you happen to be in pole position.
Track 1: Ring of Fire
Location: Krakabloa volcano