Online multiplayer will include races with multiple cars, and Codemasters plans to support up to 100 online racers in a lobby for point-to-point races.

Rather than let you go head-to-head with other players, DIRT will employ a lobby system that pits groups of up to 100 players against each other simply by comparing their times in hill climb and rally events. You'll be able to see how your current time stacks up against the competition every time you pass through a checkpoint, but while that sounds like fun, it's hardly a substitute for being able to slam opponents into trees or T-bone them on crossover tracks.

Multiplayer and Online
 
Is it true that DiRT has no multiplayer mode?
No, it’s not true. The multiplayer mode in dirt is on-line, real-time where up to 100 players compete on the same stage at the same time. There's no wheel-to-wheel racing with collisions - the multiplayer mode uses the rally and hill climb cars and tracks.
 
Is it true that there are no voice comms in the game?
There are voice comms in the game, but it's on a one-to-one basis. you pick someone to talk to while you're in the lobby waiting for the race to start
 
Does DiRT Support Downloadable Content?
There are no current plans for any DLC for Dirt.

OK, here's the deal on multiplayer.
 
There is real-time multiplayer on xbox live / PC / PSN but it's only in the "against the clock" events - Rally and Hill climb.
 
These races are hosted as large (up to 100 players) rooms, with car/track options chosen at random for a shortlist of 6 then voted on by players.
 
Private rooms can be set up.
 
These modes also work on system link/LAN
 
No split-screen
 
what's cool about this system is that with no actual "host" as such it prevents host-quitting/disconnecting-game cheating that can be a siginifcant problem in ranked online games.
 
It also keeps play flowing as the timer's always counting down to the next race. no waiting forever for the guy who's forgotten to ready-up
 
see also the long, tedious arguments about what to race next.
 
Not doing the collision-based racing means that wreckers cease to exist.
 
Basically were trying somethign different with Dirt, Taking a risk on a new idea. It does work really well, but I'm aware that (on paper, certainly) it;s not goign to be to everyone's tastes.

I have to say I'm actually pleasantly surprised at this thread - I thought things would get a lot nastier than they have.
 
As for the reasoning behind it, I can;t go too far into it- it should be borne in mind, though that we're starting from scratch here, for the first time in a long time. porting over code from RD3 or CMR2005 wasn;t really an option.
 
What also isn't an option (at thios stage) is changing the specs of this mode for release. there simple isn;t time left, I'm afraid.
 
Given that we're a relatively small independent company we've got more limited resources than the first-party studios that are held up as our main competitors. It's a source of considerable pride that we (in our opinion) can make better games than MS or sony's internal studios. but to do that we havwe to be more tightly focused, we've got to do what we can with what we've got. as far as the CMR games have been concered, multiplayer's never really been the focus (compared to ToCA/DTM/V8) so we had to decide to deploy our resources best we could.
 
Multiplayer isn't off the table for good - we've got games in the pipleine after this (no, I'm not going to tell you what they are, yet. but you'll find out very soon) and they'll be able to leverage off what Dirt's got, build on it, and improve it.