Schema: CREATE TABLE table_name_2 (class VARCHAR, rank VARCHAR, entrant VARCHAR, points VARCHAR, chassis VARCHAR)
Question: What was the class when adt champion racing ranked 1st with an audi r8 chassis, and less than 206 points?
SQL: SELECT class FROM table_name_2 WHERE points < 206 AND chassis = "audi r8" AND entrant = "adt champion racing" AND rank = "1st"