I seem to have found a bug, I only have one Gen6 car, the "NASCAR Sprint Cup Ford Fusion".
When that is the only car ticked in "set my Cars", and I select "owned cars/favourite series" the Carburetor Cup doesn't appear. If I pretend I own only the SS or Camry, it works as expected.
http://members.iracing.com/jforum/posts/list/25/3349275.page#9815839