Iowa Code § 322A.22

A condition, stipulation, or provision in a franchise prohibiting or restricting the franchisee from continuing another line-make at the dealership or adding an additional line-make to the dealership is void. This section does not limit a franchiser from establishing good cause for the termination of a franchise pursuant to sections 322A.2 and 322A.11 on the grounds that the franchisee’s dealership facility is not adequate to accommodate an additional line-make that has been added to the franchisee’s dealership.