Class A was for cars with an engine capacity over 2600cc.

Class B was for cars with an engine capacity between 1601cc and 2600cc.

Class C was for cars with an engine capacity of between 1001cc and 1600cc.

Class D was for cars with an engine capacity of 1000cc or less.

Class A was for cars with an engine capacity of 750cc or less.

Class B was for cars with an engine capacity of between 751cc and 1300cc.

Class C was for cars with an engine capacity of between 1301cc and 2000cc.

Class D was for cars with an engine capacity between 2001cc and 3500cc.

The middle class was for cars with an engine capacity from 1601 to 2500cc.

The baby car class was for cars with an engine capacity from 1001 to 1600cc.