Mich. Comp. Laws § 500.402c

Sec. 402c. (1) A certificate of authority to transact insurance in this state is not required for the sale of any travel or auto-related insurance coverages by a motor vehicle rental company or its officers or employees in connection with and incidental to the rental of a motor vehicle. (2) As used in this section: (a) "Motor vehicle" means a motorized vehicle designed for transporting passengers or goods. (b) "Motor vehicle rental company" means any person in the business of providing motor vehicles to the public under a rental agreement for a period not to exceed 90 days.