I think that almost any car can be a rally car, the only requirement is that there must be a road version that had sold a specific number of models, the brands to have competitive cars, make models that are sold by a short time, for example the Lancia Stratos, was done for rally, but it had the street version to get into rally, the 206 wrc is based on the 206gt that has the front and rear bumpers almost exactly as the WRC, but not the wide, so, as I said almost every car can be a rally car, to enter on one or another category... this is another thing of wich I dont have idea