Mich. Comp. Laws § 257.7b

Sec. 7b. "Commercial quadricycle" means a vehicle that satisfies all of the following: (a) The vehicle has fully operative pedals for propulsion entirely by human power. (b) The vehicle has at least 4 wheels and is operated in a manner similar to a bicycle. (c) The vehicle has at least 6 seats for passengers. (d) The vehicle is designed to be occupied by a driver and powered either by passengers providing pedal power to the drive train of the vehicle or by a motor capable of propelling the vehicle in the absence of human power. (e) The vehicle is used for commercial purposes. (f) The vehicle is operated by the owner of the vehicle or an employee of the owner of the vehicle.