The muscle car is over
Bloomberg's Jing Cao has the story:
There used to be a big debate about whether smaller, 6-cylinder engines disqualified Stangs and Camaros that had those motors from consideration as muscle cars. Sure, the V8 versions made the cut. But the V6s were for poseurs.
The advent of widespread turbocharging in the auto industry has changed that. Even turbo fours can serve up respectable horsepower. Who cares what you have under the hood?
There's been some talk lately that muscle cars are turning into sports cars. Business Insider's Ben Zhang made this case in his review of the 2015 Mustang GT (he had the old-school 5.0-liter V8 version, but the car has received a massive update to the way it handles, a big departure from previous generations). Muscle cars are all-American and, for their history, were supposed to get their patriotic power from big, loud V8s.
Sports cars, meanwhile, have more of a European lineage. As does turbocharging.
Younger folks don't seem to give a hoot about this distinction. A Mustang or Camaro is a fast fun car in the same way a Porsche is. For the muscle-car diehards, this brand of thinking is heresy. Give me a big V8 or give me death!
Unfortunately, the whole V8 premise - and the premise of the large-displacement, naturally aspirated engine generally - is becoming increasingly indefensible. The future belongs to fuel economy. So if you want a "real" muscle car in the 2020s, you may have to buy one used.