I don't see the turbo 4
I don't see the turbo 4 powered Mustang as being a "muscle car", but then again I don't see the GT500 as a muscle car either. Ford has done a great job over the past 30 years at redefining the Mustang. To me, a classic '60s muscle car was taking a smaller, cheaper, 2 door coupe, and stuffing a powerful V8 under the hood, resulting in a cheap car that went quickly in a straight line. It was a performance bargain. But it was also limited with so-so brakes and handling. But quickly the Mustang (and later Camaro) redefined the market by creating the Pony car, which added sportier styling, and better than average handling and braking, to it's affordable V8 coupes. In the last 20 years the target demographics changed, with many younger buyers lusting after Japanese and European sporty compact coupes and sedans, with Turbo 4 cylinder and inline 6 engines. And the V8 Mustang was targeted at BMW, with the recent 4 cyl turbo Mustang also shooting for performance cars from Europe and Japan. I don't agree with Detroit automakers killing off all of their smaller compact and sub compact cars, but without the Focus and Fiesta ST models, the Mustang now has to hold up that "entry" performance car market. Happily the current turbo 4 Mustang offers similar power and performance of V8 Mustangs of not too long ago, but without the premium price, heavier weight, and lower fuel economy of the V8 model.