Mich. Comp. Laws § 257.20a

Sec. 20a. "Historic vehicle" means a vehicle that is over 25 years old and that is owned solely as a collector's item and for participation in club activities, exhibitions, tours, parades, and similar uses, including mechanical testing, but is not used for general transportation. For purposes of this section, use of the vehicle during the period from Memorial Day weekend through Labor Day each year is considered an exhibition.