I guess in an attempt to provide a clear answer to the OP, yes, under 750.231a you can transport a firearm by having it enclosed in a case designed for tranportation and in your trunk, unloaded. However just be sure to stay off of the locations provided in 750.234d. There is also a list of places in MI that are licensed under the MI liquor contral act, Im not at home so I dont have my links so maybe another member would be able to provide you with the link.
Just stay smart and you should be fine.