What brand cars (or motorbikes) can enter the main Show on Sunday as a judged or vendor car?

While all cars are welcome as spectators, only vehicles currently part of the VW Group can enter the show/vendor areas.

This roughly comprises Audi / Bentley / Ducati / Lamborghini / NSU / Porsche / SEAT / Skoda / Volkswagen, and heritage brands such as DKW, Horch, Wanderer, etc.