I'm a member of TORC, the Trike and Odyssey Racing Club Inc, in Victoria, Australia. There aren't any trikes anymore, and most of the quads have moved to their new club (of which I'm also a member), now that Motorcycling Australia recognizes them as motorcycles!
TORC is affiliated with CAMS, the Confederation of Australian Motor Sport, which is in turn, affiliated with the FIA. What this all means, is that TORC has a responsibility for the safety of its members, in the way the race meetings are run, and the standard and specification of the buggies, all under the watchful eye of CAMS.
The club now has four classes; Mini Sprints, which as the name suggests, look like mini sprint cars, but run Suzuki RM 250 motors. Stock 250 class, which aren't really stock Honda FL 250s, as they are allowed after market pipes etc. Super Mods are the next class up, and consist of warmed Honda FL330s, and home-builts with up to 500 cc four stroke, or 400 cc two stroke bike motors.
Top of the pile (in my opinion) is Open Class, or Big Bangers as most people call them. "Open" is a bit of a misnomer really, as there are more regulations governing Open Class in the rulebook than any of the other classes! Maybe the name came about from the amount of open space they require to run in! Anyway, the capacity limits are 500 cc two stroke, and 1100 cc four stroke. These things really hoot!
I run a ZZR 1100 motor in mine, there are a few ZX9s, GSXR 1100 and 750s, YZF 1000 and R1s, CBR 1000 and 900 Fireblades, RZ 500s, a YZ 490, a KX 500, and a CR 500. As long as they are chain drive, and aren't race only specials, you can run them.
We race on a dirt track very similar to a motocross track, with jumps, tabletops etc, but no berms. Our jumps are a different shape to motocross ones, because we obviously can't throw our body weight around in the buggies, like bike riders do.
We race once a month, which gives us all time to breathe between races. We practice on the Saturday from midday. A typical race day starts at about 8 am on the Sunday with scrutineering, which is quite rigorous (I know, I used to be the Scrutineer). It's very rare that someone is asked to put their buggy back on their trailer. The drivers' briefing follows scrutineering, and then two practice laps per class of the 1.5 kilometre track. Then it's on with the racing. Each class runs five heats, consisting of six laps each.
The day ends with a de-briefing, and trophy presentations, followed by some bench racing, a couple of quiet ales.......... and a few loud ones!
The club also hosts some enduro events, run over a weekend, on a track of up to fifteen kilometres. Some of my most memorable times with TORC have been at enduros. The camping, horsing around, and general good fun all adds up to a good weekends racing!
I built a buggy with a guy in the Club, and his initiation into racing was at an enduro.….. he had a ball! You can share his experience in:

The Tale Of A Virgin Racer