Extreme class used to be the car wrecking class. This has changed at Transilvania Aventura 2015. Organizers specifically checked the most difficult passages with their own cars to be sure there is a safe way through without body damage. But participants will need front, rear and top winch (if they have one) every day.
Adventure Class went back to the roots of offroading. There was no timing for the Adventure Class. Nevertheless teams had to drive at a certain pace to complete the roadbook each day. Having no timing, this led to the old school offroad experience.