In the automotive world, few things can generate as much excitement amongst gearheads as concept cars. Automakers use concept cars to show off new design languages and engineering aspirations, giving customers a glimpse into what their vehicles might look like in five, ten, or even more years down the line.

RELATED: 10 Future Cars We Can't Wait To Drive

Unfortunately, most concept cars end up being just that - concepts that never become a reality. Restrictive regulations, high production costs, and the use of outrageous designs and technologies are some of the reasons why most concept cars never make it to production. Over the decades, American automakers have unveiled many fascinating concept cars. This list delves into ten amazing American concept cars from the 2000s that every gearhead wishes were produced.

10 Ford Interceptor Concept

Ford Interceptor Concept
Via automobilesreview.com

Ford has always had a reputation for producing fantastic muscle cars, but in the mid-2000s, the American automaker wanted to make something different - a luxury sedan that would rival any offerings from European giants like Mercedes-Benz and Rolls-Royce. The result was the Ford Interceptor Concept which created a buzz at its 2007 North American International Auto Show debut.

2007 Ford Interceptor concept car rear view
Via Cnet

The most impressive thing about the Interceptor Concept was its design - it had the sporty elegance of Ford's 1960s sedans with a bit of muscle injected into it to give it a modern, powerful look. Powering the Interceptor Concept was a 5.0-liter V8 Cammer engine pushing out 400 horsepower.

9 Cadillac Sixteen

2003 Cadillac Sixteen
Via supercars.net

In 2003, Cadillac unveiled the Sixteen Concept to cement its position as the "Standard of the World." The Sixteen was a 19-foot monstrosity designed to do two things - showcase Cadillac's future design language and serve as a throwback to the 1930s era when Cadillacs were powered by massive V16 engines.

2003 Cadillac Sixteen parked outside
Via supercars.net

This 5,005-pound car needed a matching engine, so Cadillac equipped it with a 13.6-liter naturally aspirated V16 cranking out over 1,000 horsepower and 1,000 pound-feet of torque. Though the Sixteen remained a concept, its design language was implemented in the 2008 Cadillac CTS and other subsequent models.

8 Chevrolet SS Concept

Chevrolet SS Concept
Via supercars.net

Introduced in 2003, the Chevrolet SS was a concept car intended to serve as a modern interpretation of Chevy's SuperSport heritage. The SS Concept was a contemporary four-door sedan that borrowed design cues from both modern muscle and sports cars.

RELATED: These Are The 15 Greatest Cars Made By Chevrolet

2003_Chevrolet_SSConcept
Via supercars.net

Under the SS Concept's hood was Chevrolet's race-proven 6.0-liter V8 pumping out 430 horsepower and 430 pound-feet of torque. Interestingly, the SS Concept was equipped with GM's Displacement on Demand technology which allowed it to switch between four and eight cylinders depending on driving conditions.

7 Chrysler Firepower

Chrysler Firepower
Chrysler

The Chrysler Firepower was a two-door concept car that stole the 2005 North American International Auto Show. The Firepower had a fantastic design that featured a Dodge Viper-based chassis and styling cues borrowed from the Chrysler Crossfire.

Chrysler Firepower
via motor1.com

At the heart of the Firepower Concept was an SRT-developed 6.1-liter HEMI V8 engine generating 425 horsepower, enough to propel the vehicle to 60 mph in 4.5 seconds. In keeping with Chrysler's brand image of elegance and beauty, the Firepower's interior was full of high-quality materials and meticulous details.

6 Cadillac Cien

Cadillac Cien
motor1.com

The Cien is a rear-wheel-drive mid-engined high-performance concept car unveiled in 2002 to celebrate Cadillac's 100th Anniversary. This concept car was simply too far ahead of its time - for starters, it had an experimental longitudinally-mounted 7.5-liter V12 producing 750 horsepower and 650 pound-feet of torque - which is impressive even for modern high-performance supercars.

Cadillac Cien
Via gmauthority.com

The Cien's computer-influenced driver's cockpit featured advanced technologies like Night Vision, ultrasonic rear parking assist, voice control, and LCD panel screens to display vital information.

5 Ford Shelby GR1

Ford Shelby GR-1
Via Motor1

The Shelby GR1 is one of the most interesting one-off concept cars ever built by Ford. Looking at the Shelby GR1 concept, it's easy to see why it impressed so many at the 2005 North American International Auto Show - it looked like a modern version of the iconic Shelby Daytona that's largely considered to be one of the greatest cars from the 60s.

Ford Shelby GR-1
Via Supercars.net

The GR1 was powered by a 600-horsepower 6.4-liter all-aluminum V10 engine with some components borrowed from the Ford GT. This was paired with a six-speed manual gearbox, giving the GR1 a 0-60 mph time of 3.9 seconds and a top speed of 190 mph.

4 Chrysler ME Four-Twelve

Chrysler ME Four-Twelve on the highway
Via motor1.com

When Chrysler announced the ME Four-Twelve in 2004, every gearhead's jaw dropped to the floor. This fantastic concept car had everything one could ever want in a high-performance sports car - a sleek design, a powerful 12-cylinder engine, and carbon fiber and aluminum body that kept the weight at just 2,888 pounds.

Chrysler ME four-twelve
via Chrysler

The most impressive thing about the ME Four-twelve was its power - it came with a modified 6.0-liter quad-turbocharged Mercedes-Benz M120 V12 engine cranking out 850 horsepower. With a 0-60 mph time of 2.9 seconds and a top speed of 248 mph, the ME Four-twelve would have been the fastest road-going production car had it been produced.

3 Mercury Messenger Concept

Mercury Messenger Concept
Via Supercars.net

Though the Ford-owned Mercury division was closed in 2010, it didn't go without a fight. In 2003, Mercury tried to revive public interest in its products with the Messenger Concept - an energetic and distinctive high-performance two-seater sports coupe.

RELATED: 5 Awesome Mercury Cars (5 That Helped Put Them Out Of Business)

Mercury Messenger Concept
Via blog.consumerguide.com

Under the Messenger's long hood lived a 4.6-liter all-aluminum DOHC V8 sending power to the rear wheels. When Ford finally shut down its Mercury division in 2010, it offered the one-off Messenger Concept for sale through auction with an estimated value of $75,000-$100,000. Sadly, it ended up selling for just $52,250.

2 Ford Forty-Nine Concept

Ford 49 concept
via Motor1

In 2001, Ford unveiled one of the coolest concept cars it had ever built - the Forty-Nine Concept. This beautiful concept car was penned by legendary automotive designer Chip Foose and was intended to be a tribute to the beloved 1949 Ford.

Ford Forty-Nine Concept
motor1.com

The Forty-Nine Concept had a sleek design featuring straightforward lines, clean body panels, and an all-glass upper body structure that gave it a hyper-smooth appearance. It was powered by the same Jaguar AJ-V8 engine in the Ford Thunderbird - a 3.9-liter naturally aspirated V8 sending power to the rear wheels.

1 Chevrolet Volt Concept

Chevrolet Volt Concept
via topspeed.com

Before Tesla came along with its lineup of high-performance electric cars, Chevrolet had already debuted a plug-in hybrid at the 2007 North American International Auto Show - the Volt Concept. The Volt Concept was initially intended to be all-electric, but range anxiety concerns and insufficient public charging infrastructure forced GM to make it a hybrid.

Chevrolet Volt Concept
via automobilesreview.com

The Volt Concept drew its power from a small 1.0-liter three-cylinder turbocharged engine and a 16 kWh battery pack. It could travel up to 40 miles on electricity alone which was very impressive at the time.

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