Frankenmuth Autofest Sept. 11-13 It's off of I75 between Saginaw and Flint.
http://www.michigan.org/Things-to-Do/Events/Detail.aspx?ContentID=7251A036-9780-4D4D-A713-4757C36C5F2A&city=G3054
This is a big show for auto enthusiasts. It's mostly muscle cars anda hot rods but everyone is very nice, no matter you are driving.
The whole town is cars, cars, cars all weekend with lots of cruising allowed.
If you come out that way, PM me and maybe we could hook up and talk cars. We will probably go for a little while each day as my wife has to work odd shifts.
The Birch Run Outlet store is nearby if you want to do some shopping.