1964-1965 Plymouth BarracudaGiven that the Barracuda would go on to become one of the most well-known names in Mopar history in its later model years, it may surprise some people to learn that the 'Cuda was a bit of a sales flop upon its introduction. Created to rival the rumored new model from Ford called the Mustang, it used a Plymouth Valiant as its base but added distinctive styling variations such as a huge, curving rear window sloping down to a small trunk between two vestigial tail fins. At first glance, its fastback profile almost looks like a hatchback.The 1964 Barracuda's base engine was an inline-six, but enthusiasts could opt for a 273 cubic inch 2-barrel V8. With mechanical lifters and wedge-shaped combustion chambers, this motor produced 180 horsepower and 260 lb-ft of torque at a low 1,600 RPM. This was decent power for its day, especially with the nice low-end grunt from its torque. Yet other V8s of the era outshone it, including the 289 cubic inch, 271 horsepower V8 offered late in 1964 by the Mustang.Sales weren't terrible, with Plymouth moving 23,443 Barracudas in a short model year in 1964, including both V6 and V8 variants. It would go on to sell 65,000 units in its first full model year in 1965 with a more powerful 235 horsepower V8. Nevertheless, in light of the runaway success of the Mustang, which sold 419,000 units in its first 365 days on the market, the Barracuda's debut year was not a sales success. However, Plymouth stuck with it, eventually growing the 'Cuda into one of the most beloved names in muscle car lore.1965-1966 AMC Rambler MarlinAMC always built quirky cars that stood out from the more mainstream models produced by Detroit's Big Three, but the 1965 and 1966 AMC Rambler Marlin proved too much even for AMC fans, with sales totaling only 10,327 in 1966 and a paltry 4,547 in 1966. A redesign in 1967 caused sales to fall even further to just 2,545 units, leading to the model's cancellation after that year.Its odd design obscured the fact that it was available with a pretty decent V8 that made the Rambler Marlin an early example of a muscle car. The Rambler Marlin was born from a sleek fastback concept car called the Rambler Tarpon. The concept car featured a 2+2 coupe design, but AMC executives wanted a larger, family-sized car, albeit still a two-door.The goal was to increase rear-seat headroom, but the result was an odd hybrid of a sleek, muscle car front end and a bulbous rear end, almost like two cars grafted together like Frankenstein's monster. From some angles it still looks sporty and aggressive, but from other angles it produces an effect of "what were they thinking?"This is a pity because the Rambler Marlin offered a fairly potent 327 cubic inch V8. This engine produced 250 horsepower with a two-barrel carburetor, while a four-barrel version boosted that number to 270. This made the Rambler Marlin one of the trailblazers of the muscle car era, beloved by collectors today but not dominating in the showroom when it was new.1969 Ford Torino TalladegaIt might seem a little unfair to call the Torino Talladega a poor-selling model when Ford only intended to produce a small number of them in order to qualify the model for NASCAR racing, a tactic called homologation. Still, when the dispute concerns whether 750 or 754 of them were built, it definitely qualifies as a low seller.While NASCAR teams got the version of the Torino Talladega with the feisty Boss 429 V8, street versions got the easier-to-tame but still very wild 428 Cobra Jet. With a 10.6:1 compression ratio, a cast iron block, a Holley four-barrel carb, and other street-brawler specs, the 428 Cobra Jet unleashed 335 horsepower and an earth-shaking 440 lb-ft of torque.Special bodywork allowed the Torino Talladega to ride lower to the ground for more downforce. Its Competition Suspension sported independent and unequal-length control arms, an anti-sway bar, and other high-tech components. Interiors were Spartan, stripped of most unnecessary features to save weight. Its racing genes showed in nearly every part of the car.The result was a 0-60 time of about five and a half seconds and a sub-15 second quarter mile, impressive numbers for a relatively large car. Racing models could hit 190 MPH, but street versions reached a more manageable 130 MPH. Buyers had to want a bare-bones race car, and more than enough of them did to meet the homologation requirement of 500 sales – but not much more. Today it's a highly valued classic.