On July 14th (a Friday) in Ann Arbor there is the Rolling Sculpture Car Show.
http://www.mainstreetannarbor.org/newsdetail.asp?id=20
http://www.arborweb.com/cg/t1401.html
Also in Milford every Sunday/Sunday evening between Memorial Day and Labor Day in the Baker's restaurant parking lot across from the Dairy Queen on Milford road a few miles from the I-96 and Pontiac Trail intersection there is a casual get together. Mostly American metal, a few Shelby Cobra's and Italian stuff thrown in. It's gown over the years, sometimes live music, vendors and prizes/awards given out.