Old muscle cars are cool, and some of these classic cars are more valuable than others. For example, a 1967 L88 Corvette Convertible recently went for a cool $3.2 million at the auction. A 1971 Hemi Cuda Convertible 4-Speed sold for $3.5 million while a 1962 Shelby Cobra CSX2000 can fetch over $13 million when it goes under the hammer. However, some muscle cars were shunned at the time of their production, but are highly coveted today.

So what makes a shunned classic muscle car a highly sought-after machine today? Is it its powerful engine? Is it the legendary drivers who drove these cars? Is it the badging?

10 1969 Plymouth Barracuda 440

1969 Plymouth Barracuda 440
mecum.com

Only a few examples of the 1969 Plymouth Barracuda 440 were ever built, making it one rare and valuable muscle car today. The Plymouth Barracuda 440 came with a very large engine. In fact, it was the largest power plant installed in cars in its class at that time.

1969 Plymouth Barracuda 440
commons.wikimedia.org

This V8 engine produced 375 horses and 480 pound feet of torque making the car reach 60 miles per hour in just 5.6 seconds. However, this power made the car had to launch owing to a lot of wheel spin. It also wasn’t equipped with a power steering making it hard to maneuver.

RELATED: These Are The Best Modern Muscle Cars

9 Mercury Cougar Boss 302

blue Mercury Cougar Boss 302
mecum.com

When the Mercury Cougar was introduced, it was put on a Mustang chassis. The Cougar was largely a luxury muscle car. Then, Ford made the Mustang Boss 302 in 1969. Since the Cougar rested on a Mustang chassis and all Mustang engines could fit it, it got its own version aptly named the Mercury Cougar Boss 302.

Mercury Cougar Boss 302
carscoops.com

However, the car wasn’t advertised heavily as was the Mustang Boss 302 despite being a powerful car. In 1969, only 169 copies of the Mercury Cougar Boss 302 were made, making it a valuable find today due to its rarity.

8 Pontiac Can-Am

white Pontiac Can-Am
en.wikipedia.org

When the Pontiac Can-Am was introduced in the early months of 1977, it was the most powerful muscle car at the time. It had 200 brake horsepower under the hood. This was impressive especially being introduced at a time when high compression engines were being mangled by environmental and safety laws.

Pontiac Can-Am back
streetmusclemag.com

The market loved the Pontiac Can-Am. Customers went on to place over 5,000 reservations, and so Pontiac contracted an outside company who couldn’t deliver due to equipment troubles. Pontiac grew impatient and cancelled the contract after only 1,377 deliveries.

7 Chevrolet Chevelle SS

Chevrolet Chevelle SS
en.m.wikipedia.org

The Chevrolet Chevelle SS of 1969 is quite the looker. Apart from its sheer performance styling, the Chevelle SS was equipped with a V8 engine that churned out a gargantuan 450 horsepower and 500 pound-feet of torque.

green Chevrolet Chevelle SS
autoevolution.com

This meant that it could go from rest to 60 miles per hour in just 6.1 seconds and complete the quarter mile in 13.7 seconds at 103 miles per hour. Today, this car is a rare find, and you could land a windfall should you be lucky to find one.

RELATED: 10 Coolest Classic Muscle Cars You Can Buy For The Price Of A New Mustang GT

6 Pontiac GT-37

red Pontiac GT-37
carbuzz.com

Plymouth’s roadrunner came out in 1968 to rave reviews and strong sales because of its low price, options, and wild graphics. This car was a homerun since these features appealed to the young demographic. Other companies, including Pontiac noticed, and raced to introduce their own budget-friendly muscle cars.

Pontiac GT-37
carbuzz.com

However, Pontiac took their sweet time and only introduced the GT-37 two years later. It was essentially a Tempest with a GTO engine underneath and a handful of performance options. On the outside, however, it was uninspiring as a muscle car and that let to its failure in the market. Only 2,000 examples were ever made.

5 Dodge Charger 500

black Dodge Charger 500
youtube.com

In the 1960s, Dodge had a deep desire to participate in NASCAR races. Their car that was best positioned to enter the race was the Charger. However, the Charger wasn’t able to reach high speeds because it wasn’t aerodynamic. Its concave-shaped rear glass as well as a deep grille wasn’t doing it any favors.

orange Dodge Charger 500
autoevolution.com

So Dodge went back to the drawing board and introduced the Dodge Charger 500. To improve aerodynamics, they corrected the concave-shaped rear glass and fitted it with a flushed grille. Shortly after, Dodge introduced the Daytona 500, which was more popular than the Charger 500, and that is how the 500 examples of the Dodge Charger 500 were forgotten.

4 Oldsmobile Rallye 350

yellow Oldsmobile Rallye 350
bringatrailer.com

One distinct feature of the Oldsmobile Rallye 350 is that all 3,547 examples that were ever built are yellow. They didn't just paint the body yellow, though. The whole car, including the bumper and the spoiler, was painted that color.

Oldsmobile Rallye 350
mecum.com

However, we think it looks unique and cool. It was also characterized by intelligent engineering but this didn’t help it in the market. Today, it is a very rare find, one that could make you millions.

RELATED: 10 Heartbreaking Photos Of Beautiful Muscle Cars That Were Abandoned

3 1974 Pontiac Firebird Trans Am SD 455

1974 Pontiac Firebird Trans Am SD 455
motor1.com

Due to stringent ecological and safety laws, muscle cars had practically lost all power and poise by 1974. This made them very unattractive among the masses. However, the 1974 Pontiac Firebird Trans Am SD 455 survived these laws giving us great power and impressive styling.

1974 Pontiac Firebird Trans Am SD 455
Via: YouTube

This Firebird had a restyled front as well as rear and came with an improved interior and stronger brakes. Up front, it packed a V8 engine that produced up to 290 horses in the SD trim, making it quicker than even the Corvette.

2 Mercury Marauder X-100

Mercury Marauder X-100
hagerty.comy

Mercury envisioned the Marauder as a burly, luxury coupe – one that wasn’t intended for the racetrack. It was characterized by a very long hood and hidden headlights upfront. At the back, it had a concave-shaped rear glass. However, when Mercury needed something to face the Pontiac Grand Prix, they introduced an upgraded Marauder - the Marauder X-100.

brown Mercury Marauder X-100
hagerty.com

It came with improved suspension, bucket seats, fender skirts, and a V8 engine that churned out 360 horsepower. Because it was still a bulky car, the X-100’s sales flopped only being able to deliver 8,000 examples.

1 Ford Fairlane 427

black Ford Fairlane 427
hotrod.com

Ford was eager to defeat Mopar at the drag races, so they set out to find a car that was not only large enough to fit the humongous R Code 427 V8 engine but also nimble and compact. They landed on the Fairlane and launched the Ford Fairlane 427 in 1967.

Ford Fairlane 427 blue
shannons.com.au

It put out 425 ponies and came with a light body and a potent drivetrain making it a success on the racetrack. Only 57 copies were made making it a valuable find today.

NEXT: These Modern Muscle Cars Will Soon Cost A Fortune