WMC look like they are putting the N4 with the R4 cars.
'Current Group N4 cars will be renamed as R4, in order to integrate them into the rally pyramid. This applies to all cars in the category worldwide.'
IMHO - The car rules need to be for each country/ region as each place has a different set of economic circumstances and the cars will differ, concentrate on making what is used safe and keep a ceiling on places that can afford ultra high performance cars.