Rules are somewhat indisbursed but majority of info is here: http://www.offroadexperience.com/vehiclepreparation.pdf Dominating it is a tricky. Especially for newcomers.
Teams that have done it before have advantage of knowing what to expect or just plain knowing terrain/roads/locations. Vehicle matters but not as much as in other races. This isn't really closed course race. You are on public roads all local laws apply. In 09 we had really unpleasant brush with local on aptly named Seven Devils Ranch.