Plymouth, as a marque, may have been sacrificed to let Chrysler ride through its near bankruptcy, but once it was known for its greats, like the Roadrunner and the GTX. Of course, it was also known for the biggest lemon of all, the Plymouth Prowler, so perhaps the end was nigh for Plymouth...

That said; no other muscle car reached the supremacy of the Roadrunner. The Plymouth Roadrunner could have turned into a joke considering it took a cartoon character from Warner Bros as its name and logo but turned into a legend instead because it was so good.

The GTX was another muscle car of major repute with an added touch of luxury and refinement. Both the cars flourished in the late ‘60s and early ‘70s because the oil crisis had not taken the wind out of automobile engines and horsepower till that time.

RELATED: 10 Things You Didn't Know About The Plymouth Barracuda

Still, many find it strange that the Plymouth Roadrunner and the GTX look absolutely the same, even though they were “technically” different models and priced differently as well.

So what gives? Why did the Roadrunner and the GTX look nearly identical, especially for the 1971 models?

GTX & Roadrunner Were Trims Of The Same Car

1971 Plymouth GTX
via DaytonaBeachNewsJournal

The Plymouth GTX was introduced in 1967 as the performance trim of the Plymouth Belvedere and was positioned as the “Gentleman’s Muscle Car” with plenty of refinement in the interior features.

When Plymouth introduced the Roadrunner in 1968 as the best muscle car ever, in the most stripped-down format, the GTX moved to become the most luxurious trim of the Roadrunner. But essentially, they were the same cars.

So even in 1968, the Roadrunner and the GTX looked the same, only, the price was different because the Roadrunner was as basic as the GTX was luxurious.

RELATED: The 10 Best Cars Plymouth Ever Made, Ranked

In 1971, Fuselages Of All Chrysler Coupes Were Redesigned Into More Rounded Forms

1971 Plymouth Roadrunner
via VanguardMotorSales

In 1971, the Roadrunner underwent a major design change, as did all Chrysler coupes across the board. The front fuselage became more rounded and the lights were changed as well. Since the GTX ran on the same outer shell of the car as did the Roadrunner, both the cars now looked very much the same, except that they were still branded differently.

One notable point here is that when the convertible Roadrunner was announced in 1969, sales of the GTX began to fall dramatically because now a cheaper convertible was on the market. The luxury trim was losing its appeal rather quickly.

RELATED: 10 Things You Didn't Know About The Plymouth Duster

Post-1971, the GTX Label Went To The Most Powerful Roadrunner

1971 Plymouth Roadrunner
via Barrett-JacksonAuction

After 1971, the GTX was taken off the Plymouth roster as a standalone car because of lackadaisical sales. The Plymouth Roadrunner 440, the most powerful one next to the HEMI, was rebadged as the Roadrunner GTX.

This continued till 1974 and the GTX finally retired. Post 1974 the Plymouth Roadrunner wound down into being a slightly more powerful Fury and then just a trim of the Volare.

By 1980, the Roadrunner hung up its fast-moving wheels as well, and it marked the end of an era for Plymouth and muscle cars in general.

NEXT: Here's What You Should Know About Jeep's New Desert-Rated Mojave Trim