The Heritage Center is an amazing sight to see if you're ever in the Metro Detroit area. I usually organize a tour once or twice a year for my website.
Here's a couple galleries from inside:
http://mifbody.com/gallery/index.php...r---April-2013
http://mifbody.com/gallery/index.php...our---June-1st
There's some vehicles which are the main cars in there year to year, but they also switch out some of the cars as vehicles are needed for displays at shows and events so you always see a few new cars each time you go.