There are 8 classes of vehicles currently competing in off road competition

The Classes and their definitions are:

BUGGY CLASSES
Two wheel drive buggies are manufactured with a tube frame chassis and rear mounted engine  An extensive variety of engines are used including Nissan, Toyota, Porsche and Mitsubishi  Buggies are split into the following classes depending on engine sizes

Pro Buggy - Unlimited Buggies up to 6000 cc
Prolite - Buggies - 1330 cc to 1650cc
Sportsman Buggy - Buggies up to 1330cc

TWO WHEEL DRIVE CLASSES
Extreme 2WD
A two wheel drive automobile that must substantially resemble the production vehicle it was derived from and which may be fitted with one or two seats 

PERFORMANCE 2WD
A two wheel drive automobile with provision for at least two crew members which is derived from a series production type automobile.

4WD CLASSES
Performance 4WD
4WD automobile not exceeding 6000cc which is of a series production type vehicle

EXTREME 4WD
A 4WD automobile with the original shape being from a series production 4WD