When one model has been in production for six generations, six full decades, and hundreds of models, it has numerous concepts that followed its development and showed how the designers and engineers worked. In the case of Ford Mustangs, there are dozens of different concepts and designs, some of which never advanced beyond the prototype stage. However, what forgotten Mustang concepts and ideas got lost over the years?
1. Ford Mustang I – 1962
It was a big deal when the Mustang I concept was introduced in late 1962 as a fully functional concept vehicle. This was the first time that the name Mustang was officially used, and right from the start, it was clear that the public loved the name. The connection with the Wild West mythology was a great marketing gimmick.
The Mustang I was a small two-seater roadster with a rear-mounted V4 engine from Ford Europe and a modern wedge-shaped aluminum body. The original idea behind the concept was to develop a small sports car that could compete with European imports like Triumph TR3 or MG A, but despite the favorable reaction from the enthusiasts, Ford decided to go the other way.
2. Ford Mustang Sedan – 1964
When Ford developed the Mustang in the early ’60s, it created a new model and a new class of cars—pony cars. The car looked good and retained all the classic Mustang lines and proportions, but Ford realized that it would cannibalize the Falcon’s sales since the Mustang was based on the same platform and had the same engines.
We are glad the Mustang sedan wasn’t built because the four-door model would have ruined the car’s sporty appeal and certainly affected the original model’s success. A Mustang in a two-door coupe or convertible form was an exciting and youthful performance car. Still, a Mustang in four-door version would become just another compact family sedan with no iconic appeal.
3. Ford Mustang Mach I – 1966
This car was introduced during the 1966 Detroit car show and immediately became one of the most interesting models, even though it was still just a prototype. The Mach I was the first really sporty and muscle Mustang released, and it showcased not only the 1967 redesign and sexy Fastback lines but also a new name that would be used in 1969.
With a chopped roof, square headlights, Plexiglas side windows with racing-style cut-outs, cool wheels, and a beautiful burgundy color, the Mach I was a muscle car Mustang at its finest. It captured the imagination of car enthusiasts all around the globe, and even today, it is one great-looking car.
4. Ford Mustang Mach 2 – 1967
The success of the production model gave Ford’s designers a chance to explore the sports car concept in any direction, and as soon as the first redesign of the car appeared in 1967, Ford introduced the Mach 2 concept.
This was one of several cars with the Mach name, which would later appear on the regular production version, but the shape and layout were pretty unique. The Mach 2 was a two-seater sports car with a long hood, short rear end, and a mid-engine configuration. The car was something like a more affordable version of the GT 40 race car, and it looked stunning painted in red with Shelby-style alloy wheels. Unfortunately, the concept was never produced, and Mach 2 only served as a car show item.
5. Ford Mustang RSR – 1980
The early ’80s were a strange time for performance cars. Even though the Mustang was still present in the lineup, its performance credentials had taken a hit due to the oil crisis and tightening emissions regulations. Enter the Ford Mustang RSR—a concept and one-off prototype that aimed to inject serious race-bred DNA into the Fox-body platform.
Developed with motorsport intentions, the RSR (short for “Rally Sport Racer”) was equipped with a heavily tuned V8, wide racing tires, a roll cage, and aggressive bodywork with flared fenders and spoilers. While not street-legal, this car showed that Ford hadn’t given up on performance, even in difficult times. Sadly, the RSR remained a one-off but helped pave the way for later high-performance variants like the SVO and the SVT Cobra.
6. Ford Mustang Mach III – 1993
As the Mustang approached its 30th anniversary, Ford decided to showcase the future of the pony car with a radical concept dubbed the Mach III. Based on the SN-95 platform, this concept completely departed from the angular Fox-body design and introduced a bold new styling language.
Under the hood was a 4.6-liter DOHC V8 producing around 450 horsepower, which was quite a statement for the time. With sleek, futuristic lines, integrated headlamps, dual cowl interior, and a deep green paint job, the Mach III turned heads at auto shows and previewed the styling cues that would influence the Mustang’s future. Although the production model didn’t look as wild, the Mach III showed that the Mustang was ready to evolve into the modern era.
7. Ford Mustang Lithium – 2019
What set this concept apart, however, was that it came with a six-speed manual transmission – a very unconventional pairing with an electric powertrain. The Lithium was not just about raw power; it featured aggressive styling, carbon fiber body panels, Ford Performance parts, and a low-slung stance. It hinted at Ford’s commitment to high-performance EVs and was an early sign of things to come, including the all-electric Mustang Mach-E.
8. Ford Mustang Giugiaro – 2006
When one of Italy’s most legendary design houses takes on an American icon, the result is bound to be special. The Ford Mustang Giugiaro concept was revealed in 2006 as a collaborative project between Italdesign Giugiaro and Ford. While based on the then-current S197 platform, the Giugiaro Mustang was almost entirely reimagined.
It featured a dramatic fastback roofline, scissor doors, exotic-looking body panels with exaggerated curves, and a completely redesigned interior with premium materials and futuristic touches. Under the hood was a supercharged 4.6-liter V8 good for 500 horsepower, but the show’s real star was the styling – a perfect blend of Italian flair and American muscle. Although it never made it to production, the Giugiaro Mustang is one of the most memorable and bold reinterpretations of the pony car ever created.
9. Ford Mustang GT-R – 2004
The Mustang GT-R was more than a concept—it was a race car wrapped in a concept car skin. Revealed in 2004 to celebrate the Mustang’s 40th anniversary, the GT-R was based on the all-new S197 platform and built with motorsports in mind. Under the carbon fiber hood, a 5.0-liter “Cammer” modular V8 produced 440 horsepower.
With its wide body kit, massive rear wing, exposed carbon fiber panels, and side exhausts, the GT-R was all business. Inside, the cabin was stripped out and fitted with racing equipment. This car wasn’t meant to tease production – it was a serious proposal for a future Mustang racing program. While it never reached competition as-is, the GT-R influenced the development of the Boss 302 and cemented the Mustang’s potential as a track weapon.
10. Ford Mustang GT Concept – 2003
Before the Mustang GT-R stunned crowds in 2004, the 2003 Mustang GT Concept laid the foundation for one of the most successful modern redesigns in the model’s history. Unveiled at the 2003 North American International Auto Show in Detroit, this concept previewed the upcoming S197-generation Mustang and boldly and modernly reintroduced retro styling.
The car was immediately praised for blending classic Mustang design cues—such as the long hood, short rear deck, and iconic tri-bar taillights—with aggressive, contemporary proportions. Under the hood sat a 4.6-liter supercharged V8 making around 400 horsepower, mated to a manual transmission. Inside, the GT Concept featured brushed aluminum, leather, and throwback design elements, echoing the ’60s Mustangs while staying true to the early 2000s vibe.