The variety of classes, divisions and categories in the hillclimb sport is hard to understand. I have tried to put the class structures of the major championships in a single table. You can now view my efforts for the European Championship, the European Cup, the FIA Hillclimb Masters and the national championships of Austria, Belgium, France, Germany and Spain.
Sadly, in my opinion it still looks rather messy. Advice, corrections and/or critism is always welcome.