Here’s a link to the OP of the 1970 Nurburgring competition. Your body appears in the list of cars which are considered “not in the spirit of competition” or “Wonky aero”
Link to Der Bayer’s racing competition
Since a body based on an early 3 series could hardly be considered cheating of itself, this would only leave OP aero characteristics or the body looks too modern to suit the aesthetic of the race line-up Der Bayer is aiming for… Maybe PM him to determine his rationale for putting the car on the list?