326.9  Individual vehicles not to be proportionally registered.
  The registrations of individual vehicles shall not be subject to proportional registration with this state. The same fleet, consisting of the same vehicles in each state, shall be proportionally registered in each state with which the fleet is prorated; and every one of the vehicles shall be included in the fleet in each state. Failure to comply with these requirements shall constitute grounds for cancellation of proration privileges.
[C71, 73, 75, 77, 79, 81, §326.9]