In 2019 the FIA rally commission presented a radical overhaul to the rally pyramid to introduce common nomenclature and structure of the international championships and car classes used across the sport in a similar way to terminology used in formula racing.
At the top of the pyramid, Rally1 describes elite level of driver aptitude and car performance in the World Rally Championship (WRC).
[1][2] Each of the new tiers of the pyramid align numerically with the existing FIA sporting classes introduced in 2014.
[5][6] The relaxed rules in the kit car category also resulted in unfair competition and high development costs with some manufacturers using it to promote their two-wheel drive models instead of entering the main WRC manufacturer class.
The FIA introduced a new Junior World Rally Championship in 2001 solely for the Super 1600 cars.
During the years 2006 to 2012, the Intercontinental Rally Challenge ran featuring the same mix of cars as the World and European championships.
In 2013 it effectively merged with the European Rally Championship when promotor Eurosport took on the promotion rights for the latter.
The FIA abandoned this idea and no new R4 cars were homologated after 2015 as R4-Kit was the preferred path, R4 could then not be run in Europe.
This resulted in star drivers in R5 factory teams in the same sporting class as privateer enthusiasts who had built their own R4 car.
This car could not be run by anybody other than the manufacturers registered in WRC and drivers had to receive approval by the FIA.
Volkswagen left the WRC championship after their diesel emissions scandal, followed by Citroën in 2019.
Lower costs and new technologies were cited in calls for a new car used in the manufacturer's championship.
Each regional championship outside Europe permits additional local cars to compete and this will likely continue with the intended goal of enhanced participation.
The biggest differences between each group of cars is the performance and the costs involved to manufacture, run and maintain them.