From my recollection of reading the laws here:
http://www.legislature.mi.gov/documents/publications/firearms.pdf
A vehicle for concealed carry purposes is basically anything with a motor. But my memory could br wrong, I wouldn't trust it. It'd look in the above PDF carefully.
Consult 750.227d:
750.227d Transporting or possessing firearm in or upon motor vehicle or self-propelled vehicle designed
for land travel; conditions; violation as misdemeanor; penalty.
Sec. 227d. (1) Except as otherwise permitted by law, a person shall not transport or possess in or upon a
motor vehicle or
any self-propelled vehicle designed for land travel a firearm, other than a pistol, unless the firearm is unloaded and is 1 or more
of the following:
(a) Taken down.
(b) Enclosed in a case.
(c) Carried in the trunk of the vehicle.
(d) Inaccessible from the interior of the vehicle.
(2) A person who violates this section is guilty of a misdemeanor, punishable by imprisonment for not more than 90 days, or
a fine of not more than $100.00, or both.
History: Add. 1981, Act 103, Eff. Mar. 31, 1982.
I'll let the lawyers figure this one out...