Michigan Compiled Laws, Chapter 435. Sundays and Holidays § 435.251

Sec. 1. It shall be unlawful for any person, firm or corporation to engage in the business of buying, selling, trading or exchanging new, used or second-hand motor vehicles or offering to buy, sell, trade or exchange, or participate in the negotiation thereof, or attempt to buy, sell, trade or exchange any motor vehicle or interest therein, or of any written instrument pertaining thereto, on the first day of the week, commonly called Sunday.