If I might just bring back the Off-roader issue raised a few pages back, I would like to say this:
There are some stock cars that could feasibly compete(and do so) in off-road races. Examples are ineed the formidable Mitsubishi Pajeros, but I'd also like to suggest that the turbo-diesel Landcruisers(especially the 70 Series models) sold in Australia and South Africa, not the rubbish 4.7 litre petrol car sold in North America. That's just a fat luxury car, in the same vein as the Rav4, the Forester, the Ford Territory(an Aussie 6 cylinder sedan in a fat-suit) and the upcoming Mazda CX-7.
Pajeros, Landcruisers, Nissan Patrols, Land Rover Defenders(despite the frequent break-downs). Real off-roaders, and potentially really good off-road racers. However, the faster, Dakar-style cars won't work. A big course like that won't work in LFS. Whay might work for all concerned is a course on sand, like used by the bored people of Alice Springs. A desert rally circuit that's been left for a few years, bit of red dust, screaming diesel engines. Perfect.