Concept cars are a way for automakers to test out cool new technical and design features, but also to just show off from time to time. Sometimes the resulting vehicles get to go into production, other times they don’t. The following list has gathered some of the former, amazing concept cars we will never see on the roads:

20. Audi Rosemeyer

Inspired by the Auto Union Silver Arrows Grand Prix racers of the 1930s and named after a famous racing driver of that era, the Audi Rosemeyer is a mix of the German manufacturer’s rich heritage with modern design elements. Initially showcased during 2000, Audi decided against putting the Rosemeyer into production due to high costs and an unwillingness to create competition with sports cars from its then newly-acquired Lamborghini.

19. Renault DeZir

Renault’s DeZir is an electric concept car unveiled during the 2010 Paris Motor Show. Its electric motor outputs a relatively modest 150 horse-power, but what it lacks in strength is surely makes up with its looks. It is an elegant two-seat coupe with butterfly doors, with a bright red livery – a definite head turner if ever released by the French automaker.

18. Kia GT4 Stinger

Kia is not exactly known for producing sports car, but this might change if something like the GT4 Stinger ever goes into production. It is a sleek, 2+2 rear-drive coupe with a 2.0-liter turbocharged four-cylinder that outputs about 315 horsepower. It doesn’t look like the Korean manufacturer is looking to enter the sports car market any time soon, however.

17. Holden Efijy

Designed by the Australian automaker Holden (a subsidiary of GM), the Efijy was created as tribute to the iconic Holden FJ, but also as a showcasing of the company’s design and engineering skills. Never intended for production, a great deal of care was nevertheless put into its creation, the end result being a very stylish, distinguished-looking vehicle.

16. Jeep Hurricane

Touted by its creators as “the most maneuverable, the most capable and the most powerful 4×4 ever built”, the Hurricane is quite an amazing piece of engineering. Equipped with two 5.7-liter HEMI engines which deliver a total of 670 horse-power, with a lightweight yet durable carbon fiber body, you would’ve almost been sorry to ride through the dirt of these had Chrysler ever decided to release any of them.

15. Mercedes F4 Carving

Mercedes dazzled during the 2001 Tokyo Motor Show with the F400 Carving concept – and it wasn’t all about the car’s bold, sporty looks. It employed a multitude of interesting systems, with the stand-out being a feature that lets the wheels actually tilt up to 20 degrees from vertical, for added stability when turning. Only envisioned as a concept study, the F400 was never considered for release.

14. Cadillac Sixteen

The Cadillac Sixteen look as futuristic now as it did when it was first revealed in 2003 – which is one of the reasons why it was used in the sci-fi flick Reel Steel, set in 2020.

This ultra-luxurious vehicle is something of a gentle giant, with its 13.6-liter V16 engine churning out over 1000 horsepower, but sadly all we will ever see on the road is the influence it had on subsequent Cadillac models.

13. Maserati Birdcage 75th

The brainchild of the world-renowned Pininfarina, the Maserati Birdcage 75th was created to celebrate the 75th anniversary of the Italian car design company. The vehicle itself has the look and vibe of a spaceship, with a head-up display and a bubble canopy instead of doors giving it a futuristic, if unpractical feel.

12. BMW GINA

Innovative, unique, strange – words usually used to describe concept cars, but never have they been so appropriate in describing one such as in the case of the BMW GINA Light Visionary Model. Unveiled in 2008, its name stands for Geometry and functions In ‘N‘ Adaptations, which is sort of a roundabout way of saying the car is a shape-shifter. That’s right, this unusual vehicle has a body made of fabric which is stretched over a movable metal frame.

11. Toyota FT-HS

When the Toyota FT-HS (which stands for Future Toyota Hybrid Sport) first appeared at the 2007 Detroit Motor Show, it seemed it could be the long-awaited successor to the iconic Supra. Unfortunately, this stylish sports car with its 3.5-liter hybrid-electric V6 engine was never taken beyond the concept phase, while the new Supra is nowhere near close to release as well.

10. BMW M1 Homage

The BMW M1 was one of the best sports cars of its day, so the Bavarian manufacturer decided to celebrate the model’s 30th anniversary with the 2008 M1 Homage Concept. The new vehicle features the same low and flat, yet unfortunately BMW hasn’t released any of its technical specs.

9. Mazda Furai

The Mazda Furai (a name which translates to sound of the wind) is nothing short of stunning. After its debut at the 2008 North American International Motor Show, it was rarely showcased before disappearing completely later that year. Sadly, the reason for this is that the Furai caught fire in August 2008, so this is one car we will probably never see again at all, neither on the road nor on display.

8. Ford Shelby GR1

Unveiled at the 2005 North American Auto Show in Detroit, this great creation from Ford bears a well-known name in the world of motorsports – that of the famous driver (and later car manufacturer) Carroll Shelby. It is the epitome of sporting, with sleek lines and an aggressive look, but was shelved by the Detroit-based manufacturer who preferred to focus on mainstream vehicles after falling on hard times a few years ago.

7. Hummer HX

6. Lamborghini Estoque

When you say Lamborghini you immediately think of two-seat supercars, but for once the people in charge at the Italian manufacturer decided to think outside the box and create the Estoque, a four-door luxury sedan. Though Lamborghini might be a bit out of its comfort zone with this one, the Estoque still looks great and would’ve probably been an interesting experiment if ever released.

5. Saab Aero X

Unveiled during the 2006 Geneva Motor Show, the Saab Aero X is so awesome-looking that it was speculate it would appear in the Transformers sequel. It never got to make its film debut and it seems the Swedish manufacturer has no plans of ever taking the Aero X beyond the concept stage, yet this 650-horsepower, ethanol fueled beauty clearly has the makings of a movie star.

4. Chrysler ME Four-Twelve

If it had been developed further than the concept stage, Chrysler’s ME Four-Twelve might have been one of the great cars of the last decade. A two-seat, two-door, mid-engine vehicle with a 6.0-liter V12 powerplant churning out 850 horsepower and with an ultra-lightweight carbon fiber and aluminum structure, it had both the looks and the specs of an incredible supercar. Sadly, high costs and uncertain times for the American manufacturer mean the ME Four-Twelve had to be shelved indefinitely.

3. Aston Martin DBC

Sophisticated, suave and strong, Aston Martin is the James Bond of automobiles, something quite apparent in the DBC concept. Unusual for the British manufacturer, known for its excellent grand tourers, the Aston Martin DBC features a mid-engine layout – but that’s what concept cars are for, right?

2. Lamborghini Egoista

Built to celebrate the company’s 50th anniversary, the Lamborghini Egoista is simply outrageous (but in the good way). According to its lead designer, “it represents hedonism taken to the extreme”. It only has one seat (egoista is, after all, Italian for selfish) and looks more like a bull ready to attack than anything else Lamborghini has ever released.

1. GT by Citroën

The GT by Citroën is what you get when you let a Japanese racing simulator developer (in this case, Polyphony Digital) play with the people over at Citroën. Unveiled at the 2008 Paris Motor Show, it truly looks amazing and has the technical capabilities to match. Sadly, the French automaker decided against producing any real versions, although it pondered the manufacturing of a handful of $2.1 million GTs for a while.