Several American cars shot up in value since their introduction. When the 1967 Shelby GT350 made its debut, the car was priced at $4,000. This would be the equivalent of $35,480 today when adjusted for inflation. However, a '67 Shelby GT350 in fair condition is a $310,000 machine. This amount would be around $35,000 in 1967.

RELATED: 15 Cheap Cars That Are Appreciating In Value Fast

Figuring out how to determine if a car will go up in value can be a tricky process. American car companies released a myriad of vehicles that performed amazingly over the decades, while others simply tanked. Moreover, several sought-after classics were just ordinary cars during their era. Several American cars deemed average are now seeing their value go up.

10 1987 Buick Grand National

1987 Buick Grand National Cropped
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The American muscle was slowly dying during the 1980s. In 1984, the Chevy Corvette came stock with a 5.7L L84 V8 rated at 205 hp. Things did not improve as in 1986, Pontiac equipped the Firebird with a 5.0L V8 developing 150 hp. To put bluntly, the muscle car scene was in shambles. One of the few brands producing some decent all-American cars was Buick.

RELATED: Why This 1987 Buick Grand National Isn’t Quite What It Seems

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The Grand National is one of the greatest Buicks of the '80s. Its retro and boxy look transcended the years. The best part about the Grand National is the turbocharged 3.8L V6 rated at 245 at 4,000 rpm and 355 lb-ft of torque at 2,000 rpm. After the GNX made a comeback a couple of years ago, the Grand National started shooting up in value.

9 1992 Dodge Stealth R/T

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Dodge introduced its legendary Viper in 1991. Being one of the few sports cars in Dodge's lineup, the carmaker quickly realized that it was imperative to include something far more affordable. Domestic car companies started badge-engineering several of their existing and new nameplates in the '80s. The trend remained heavy until the early '90s.

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The Dodge Stealth R/T Twin Turbo is bonkers. The top trim level comes with a twin-turbocharged 3.0L 6G72 V6 rated at 300 hp at 320 hp at 6,000 rpm and 315 lb-ft of torque at 2,500 rpm. However, these numbers were not enough to attract domestic gearheads. Despite being a badge-engineered Mitsubishi 3000GT VR-4, the Dodge Stealth R/T remains a true gem that is not depreciating as fast as other forgotten cars have.

8 1996 Chevrolet Impala SS

Black 1996 Chevrolet Impala SS
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Cars such as the Dodge Charger Hellcat and the Cadillac CT5-V Blackwing are the best muscle sedans on the market. Their respective success eclipsed muscle sedans from yesteryear. Chevrolet released one of the most remarkable big-body muscle sedans. The Impala SS was a beast that muscle heads will always remember fondly.

RELATED: 10 Reasons Why We Love The 1996 Chevy Impala SS

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The 1996 Chevrolet Impala SS is the ultimate muscle sedan of the '90s. Fitted with a naturally-aspirated 5.7L LT1 V8 developing 260 hp at 5,000 rpm and 330 lb-ft of torque at 2,400 rpm, the Impala SS was far more interesting than other American performance sedans at the time. According to Hagerty, a '96 Impala SS in concours condition is worth around $51,800.

7 2001 Oldsmobile Aurora V8

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Oldsmobile was no longer relevant by the time 2001 came about. The American carmaker completely lost the plot during the late '70s and early '80s. While Oldsmobile went above and beyond to find its new position in the market, it failed to retain its supporters and offer vehicles people would love. With that said, Oldsmobile did produce a textbook sleeper before going extinct.

2001 Oldsmobile Aurora V8 2 Cropped
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Oldsmobile was on the verge of collapse by the time the Aurora became more interesting. Oldsmobile moved forward with a naturally aspirated 4.0L L47 V8 capable of producing 250 hp at 5,600 rpm and 260 lb-ft of torque at 4,400 rpm. The Aurora V8 was Oldsmobile's very last vehicle that deserved attention. Consequently, the more nervous Aurora V8 will most likely become a collectible in years to come.

6 2003 Mercury Marauder

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Mercury made its debut in 1938 when Edsel Ford decided to include a mid-range brand in Ford Motors' portfolio. Although Mercury cars tend to fall under the radar, the company manufactured several cars that pack a mean punch. One of Mercury's greatest nameplates, the Marauder, is one American car that is attracting more and more car fans as time goes on.

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The Mercury Marauder was the muscle sedan of the early 2000s. Using the same body as the Ford Crown Victoria, the Marauder proved that Mercury was once a step above Ford. The Marauder is easily recognizable as it looks fiercer than the Crown Vic. Underneath the hood sits a naturally-aspirated 4.6L Modular DOHC V8 that pumps out 302 hp at 5,750 rpm and 318 lb-ft of torque at 4,250 rpm. The last Marauder will be a cool retro muscle sedan in a decade or so.

5 2006 Pontiac GTO

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Defunct carmaker Pontiac was once one of the most promising car companies in the United States. Until the mid-70s, Pontiac was at the top of its game. Releasing one instant classic after the other, the Detroit carmaker was the best alternative to Ford's and Chevy's sports cars. As time went on, Pontiac lost its magic. Before its demise, Pontiac tried one last time to show that it still got it.

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The Pontiac GTO is among the many American cars that gearheads wish had succeeded but didn't. The last GTO looked like a bar of soap. It was, around that time, one of the blandest muscle cars. However, things were quite interesting in the power department. The GTO came stock with a 6.0L LS2 V8 rated at 400 hp at 5,200 rpm and 400 lb-ft of torque at 4,000 rpm. The GTO flopped in when it was released, but it will likely become valuable in the future.

4 2008 Dodge Magnum SRT-8

Red 2008 Dodge Magnum SRT-8
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Dodge shook up the car scene of the mid-2000s. Unlike Ford and Chevy, Dodge successfully brought back nameplates from yesteryear. The Magnum, followed by the Charger and the Challenger, received a lukewarm welcome. With that said, gearheads nationwide learned to love these outstanding Dodge cars. However, the Magnum was not given enough time.

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The Dodge Magnum SRT-8 was hilarious to some, but true petrol heads noticed its huge potential. Unfortunately, the Magnum was released at the wrong time. Station wagons were no longer the go-to family cars, and the Great Recession negatively impacted American households' wallets. A gas-guzzling wagon equipped with a 6.1L HEMI V8 churning out 425 hp at 6,000 rpm and 420 lb-ft of torque was doomed to fail in 2008. After manufacturing 232 units, Dodge stopped production.

3 2008 Saturn Sky Redline

2008 Saturn Sky Redline Roadster
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Mercury is well-known in the car scene. Saturn, on the other hand, is not. Owned by GM, the forgettable car brand was founded in the late '80s. Saturn cars are not memorable as nothing out of this world was ever manufactured. Going for the badged-engineering option, GM offered the Saturn Sky Redline. Though forgotten, the Sky Redline remains a terrific roadster.

2008 Saturn Sky Redline
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When taking a look back at the underrated Saturn Sky Redline, it is fair to say that it was going to fail. Despite its cool physique taken from the Opel GT, the Saturn name was already synonymous with snooze fest. The Sky Redline was slightly different. The roadster came stock with a turbocharged 2.0L inline-four 260 hp at 5,300 rpm and 260 lb-ft of torque at 2,500 rpm. The Sky Redline may one day end up becoming the new AMC Gremlin.

2 2009 Cadillac XLR-V

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Cadillac is America's most luxurious car brand. The Detroit carmaker produced numerous outstanding vehicles since its creation. From the Series 61 to the most recent CT5-V Blackwing, Cadillac never failed to design breathtaking cars. Although Cadillac is one of the most revered American car brands, the company did make a handful of mistakes along the way.

RELATED: These Are 10 Of The Coolest Cadillacs Ever Made

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It is safe to say the Cadillac XLR-V was an abject commercial failure. Instead of moving forward with an altered version of the LS7 or LS9 found on the Corvette C6 Z06 and ZR1, Cadillac adopted a supercharged 4.4L Northstar V8 rated at 443 hp at 6,400 rpm and 414 lb-ft of torque at 3,900 rpm. Even if Cadillac never reached its sales projections, the carmaker created a performance car that will likely become a classic in a decade or two.

1 2010 Ford Taurus SHO

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The domestic car industry underwent several changes. As a result, it became increasingly difficult for American companies to design cars that would directly rival Japanese and German imports. Ford did whatever possible to adapt to those changes and to find ways to cut the grass under Japanese and German car companies. One of the cars that helped Ford achieve that is the Taurus SHO.

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There are several things gearheads forgot about the Ford Taurus SHO, such as the fact the very first Taurus SHO hit the streets back in 1989. The SHO was the first decent muscle sedan made by Ford. In 2010, Ford reiterated the experiment. This time around, the Taurus came stock with a twin-turbocharged 3.5L EcoBoost V6 capable of developing 365 hp at 5,500 rpm and 350 lb-ft of torque at 3,500 rpm.