As mentioned in the first post, a Muscle Car is an American made car.
Many will say if it is not built in America, with American parts and by an American company... it is not a Muscle Car. The Muscle Car is supposed to embrace, pay tribute and salute American engineering as well as being considered a signature staple of the American culture. Unfortunately, that culture ended in the late 70's thanks to the EPA, ever encroaching regulatory over-reach of the political Left and either total buy outs or merging of American car companies with foreign interests, leading to a massive outsourcing of assembly and part manufacturing out of country.
Agree but with the globalists pushing one world economy for decades now, about the best we can say today is "made by an American Corporation".
Well, except Fiat/Dodge now.
Me personally, I think Pony Cars are muscle cars (Muscle Car Club agrees), but they would fall on the lighter side of the category, as they were much more nimble on corners and did not have a big block motor in them, at least not in the common production vehicles. Though some limited production Mustangs had engines such as the 428ci, most cars were equipped with a 289-302..
That's how I always viewed Pony Cars.