@Rick Perhaps “the physical appearance of a past era” translates into the appearance of a vehicle, thereby being a part of a styling language. That’s a small difference, as the result is appearance, i.e. exterior styling.
Outside the PT Cruiser, the Mustang was the vehicle that brought it back — the Camaro and Challenger followed. But the Mustang, as @Grawdaddy pointed out, is leaving that part of the design realm, and the Camaro may follow suit.
Retro happened — and will continue to happen in the future (over the next 5-10 generations of vehicles); but it would seem that for this and the next generation, it’s on the way out.
