The British Touring Car Championship technical rules are interesting and derived from a need to have a wide selection of cars entered without huge development costs. There are specified transmissions & suspension parts like hub uprights and strict controls on engines, with the option of using a championship spec engine from a single supplier, if the car manufacturer/team doesn't have a suitable engine or doesn't want to develop their own. The bodyshell is from any suitable production car, but the bits underneath are closely controlled to keep costs down and the championship open. Could this work in WRC?