Mopar’s mid-1960s to early 1970s run of muscle cars easily goes down as one of the greatest eras ever for an American performance car maker. The Dodge and Plymouth brands of this period sold some of the most iconic muscle cars ever made, with model names every bit as recognized as the cars they adorned. Filling showrooms at this time were the Charger, the Challenger, the Cuda, the Super Bee, and the Demon, just to name a few.

While certainly not obscure or forgotten, the Plymouth GTX is a model from this period that sometimes gets overlooked when compared to its siblings. In the mid-’60s, as the muscle car movement was taking off, the mid-sized GTX would help lay the groundwork for the Mopar muscle cars that would follow it. The GTX also developed an image as a “gentleman’s muscle car” or “gentleman’s hot rod” through Mopar’s marketing and its higher price — and more well-appointed nature — compared to other mid-sized muscle cars of the time.

While there are other late ’60s and early ’70s American performance cars that could also lay claim to the “gentleman’s muscle car” label, the Plymouth GTX’s blend of upscale luxury and drag-strip-ready performance certainly made it stand out among its Mopar muscle car contemporaries. Today, this also makes the GTX a very desirable piece of muscle car history for collectors.

While the definition of what exactly is or isn’t a muscle car is loose, the Chrysler Corporation had been building high-performance, V8-powered automobiles since the mid 1950s, and it really began ramping up those efforts in the early and mid 1960s. By 1967, muscle car fever had begun to sweep the industry, with automakers rolling out a stream of specially-marketed and packaged, mid-size models powered by large cubic-inch engines.

The GTX debuted for the 1967 model year as Plymouth’s mid-sized muscle offering. Based on the Belvedere, the GTX came with big block power as standard, offering buyers a choice between the base 440 cubic-inch Super Commando V8 and the legendary 426 Street Hemi. Beyond its power plant, the GTX came well-equipped inside and was adorned with hood scoops to help it stand out in the growing segment of mid-sized muscle offerings.

It was in 1968, though, when the GTX really began to separate itself as Plymouth’s more upscale muscle car offering. That’s because this is the same year the legendary Plymouth Road Runner debuted. Based on the same mid-sized Belvedere body style, the Road Runner was all about stripped-down, budget-friendly big-block performance. This meant that GTX was now Plymouth’s better-equipped, more upscale take on the mid-sized muscle car, available with engines like the aforementioned 426 Hemi or the potent 440 Six Pack. 

While there wasn’t any specific or official branding of the GTX as the “gentleman’s muscle car,” it was marketed as part of the “executive branch” of Plymouth’s so-called Rapid Transit System muscle car lineup alongside the full-size Sport Fury GT. However, just because it was positioned upmarket didn’t mean the GTX lacked the fun of other Mopar muscle cars. It still had the same bright color options and wild optional features like the Air Grabber hood scoop. The GTX existed as a standalone model until 1971, by which point the muscle car era itself was already beginning to fade out. 

Because there’s no official “gentleman’s muscle car” title, there are several other muscle-era models that could also be deserving of the label. These included the well-equipped Oldsmobile 442, the early 1970s Pontiac Grand Prix, and the related Chevrolet Monte Carlo, all of which were General Motors offerings. The latter two, in particular, matched big cubic-inch muscle car engines with elements of the emerging personal luxury car segment. 

Luxury muscle wasn’t solely the domain of mid-sized offerings, though, and there were also full-size offerings that blended muscle car and luxury features. These include the aforementioned Plymouth Sport Fury GT and the rare Chrysler 300 Hurst Edition, both of which added some muscle car spice to spacious and upscale full-size coupes.