In the 1970s, semi-trucks had shutters in Alberta Canada.
My father once brought home a approx 18"x18" scaled down model of the shutters being sold for large trucks. All aluminum, and very heavy duty. They were sold for the fronts of semis to provide better heat control and thus improved engine efficiency.
I'm back - I found them
BorgWarner makes truck shutters (look just like they did 30-40 yrs ago!)
http://www.ets.borgwarner.com/pages-...-shutters.html
Better pictures here...
http://www.ets.borgwarner.com/PDFs/Shutters.pdf
Maybe it will give you some ideas!