RE: GMC Challenger?
Not to be Debbie Downer here, but... The German designed platform that Chrysler "borrowed" from the E-class Mercedes whilst under the thumb of Daimler, and the Aussie designed Zeta platform that the all-new Camaro will be riding on are BOTH being built in Canada.
The only REAL, AMERICAN Muscle Car is designed and built in Flat Rock, Michigan. 1964-Present, Baby! Just to add insult to injury here, but did I mention Mustang is the only convertible being offered in the segment? That's a low blow, I'm sorry.