This was posted by a forum VIP over at forza motorsport 2 forums. He writes :
Hey guys, in regards to car clubs in Forza 2...
It's true that we couldn't get that feature into the game, but some things to keep in mind is that multiplayer games still support team racing so you can still have club battles on Live. I realize what you lose without car club support is the ability to see in any official capacity which are the top clubs running in the game. One of my goals for post-launch FM.net is to implement a feature that allows players to register their car clubs on this website, with the ability to administrate memberships, etc., and then host official car club scoreboards on FM.net based on your club's cumulative rankings.
There's a lot we need to spec out and I'll be working with Turn 10's designers to make this happen. I'm not going to promise when we can roll this feature out but consider implementing car clubs FM.net's first DLC priority. Also, after I discuss with the webdevs the feasibility of car clubs on FM.net, I'll create an official thread to gather ideas you guys may have about how to make it useful as well.
Thanks, and sorry if this tidbit of news has disappointed anyone.