For the 2013 American Muscle Calendar, customers with the best looking Mustangs in the US were found via the company's Facebook page. Models sourced include everything from a classic Mach I through an 80s-era Fox-body to the modern Iacocca edition. The cars were then shot with scorching hot AM girls, who were later treated to some burnouts and donuts. Watch the behind-the-scenes video to check out all the action.