Some concept cars pave the way for the industry's future, but some are beyond ridiculous.

Concept cars from auto manufacturers are always ahead of their time, with futuristic and outlandish designs that leave everyone surprised but impressed. Engineers pull out all the stops when designing concept cars for the future of their brand. As a result, concepts are superior and unique in every way. Their ludicrous looks are only the tip of the iceberg, as they boast technology and features that have never been fathomed. That is why concepts get the automotive world so riled up, even if they rarely go into production, or undergo radical changes if they do.

However, the pre-production stage is where all the fun lies, and where the engineers and designers do most of their flexing. Some concept cars come and go, and become forgotten, but there are some which take everybody by surprise, owing to their features, their looks, or both. In that vein, here are 10 cars and concepts that surprised everyone.

It was designer Chris Pollard who created and showcased the Jaguar Mark XXI in 2009. The concept was an example of luxury blending with eco-technology, and well, it certainly looked weird. The entire design of the car was in the shape of a leaf.

The exterior had photo-voltaic panels, resembling leaves, which could automatically change positions according to wherever the sun was. These panels would charge the car when stationary, and of course, the interior was as luxurious as possible. The Mark XXI was a Jaguar, after all.

World-renowned designer Giorgetto Giugiaro was the man behind the Caimano concept from Alfa Romeo in 1971. He fitted this concept car with a 1.2-liter flat-four engine which he took from the Alfa Romeo Boxer. This design was as unique back in 1971 as it is today.

The Caimano featured a cylindrical dashboard, pop-up headlamps, and two small windows carved into the front doors of this two-door concept. Even the windshield was extremely unique, stretching out from the top of the bonnet to the very center of the roof, with the doors of the Caimano being integrated into the roof panel itself.

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Bentley showcased the Hunaudieres concept just before the turn of the century in 1999, naming the car after the straightaway at Le Mans. When the VW group took over Bentley, they decided to make the brand more popular, and the Hunaudieres was their first step in that direction.

A modified engine churned out 623 horsepower and 560 lb-ft of torque, which are figures which are still massively impressive, let alone 23 years ago. Sadly, however, the concept car never made it to production. There are several ways the Hunaudieres could have changed Bentley's brand image for the new century, but we would never know for sure now.

MIT and Lamborghini had partnered up for three long years, and the result of that partnership was the Lamborghini Terzo Millennio. Lamborghini stated that the Terzo Millennio was the supercar of the sustainable future, built on four pillars.

These four pillars of the Terzo Millennio are Energy, Innovation in Materials, Powertrain and Vehicle Architecture, and Sound and Emotion. The Italian marque visualizes the Terzo as the car for the third millennium. While all-electric, the Terzo Millennio doesn't use batteries but instead employs supercapacitors in its four electric units. The exterior design is as outlandish as Lamborghini gets, of course, with the unique carbon fiber shell being capable of self-healing.

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Hyundai is not a name one usually associates with luxury, but the brand's luxury division surprised the world with its concept of the 21st-century grand tourer, the Genesis Essentia. Revealed four years ago, the Essentia is an all-electric concept, with an unprecedented design in Hyundai's or Genesis' history.

Genesis was able to quote a 3-second 0 to 60 time for the Essentia, and today, the concept is closer than ever to finally reaching fruition in its production stage. Only time will tell if the Genesis Essentia can retain every trait from its concept and if the market will accept this EV grand tourer.

German designer Anne Forschner trained at BMW, Mercedes-Benz, and Mazda before she went on to create the BMW Lovos concept. An extremely outlandish and futuristic BMW concept, the Lovos was an acronym for Lifestyle of Voluntary Simplicity.

This was a green car concept, and Forschner intended to urge people to think and accept things outside the box. The BMW Lovos used 260 interchangeable and identical scales, all of which acted like small solar panels when closed. The same scales functioned as brakes for the Lovos, and even the wheels themselves were made of 12 scales each.

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In 2006, Mazda revealed its Nagare concept at the Los Angeles Motor Show, which got its name from the Japanese word for 'flow'. The lead designer behind the Nagare stated how the concept car celebrated "proportions and surface language". Keeping with its name, the Nagare's body was surprisingly smooth.

The lines of the Mazda Nagare flowed like liquid across its unibody design, and massive wheels filled the wheel arches. Even the windshield flowed from the front to the back, making up the roof and well as the windows of the Nagare. The Nagare ran on Mazda's hydrogen-fuelled rotary engine.

Mercedes-Benz created the F 015 as more of a research car rather than a concept car, but it remains a hugely different design than anything the brand had ever made. Revealed in 2015, the F 105 was a self-driving concept car that was able to detect pedestrians through lasers behind the logo.

The Silver Arrows on the F 105 were also projectors, and with two rear suicide doors and all-metal windows, the Mercedes-Benz F 105 was quite an endearing concept. Being Mercedes, the marque fitted it with plenty of luxury on the inside, with elegant usage of aluminum, leather, and timber in the cabin.

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It has been fourteen years since the BMW Gina roadster was revealed, and it is still as surprising a technological marvel as it was then. The Gina concept car changed its shape as per its surroundings and speeds. The name Gina actually stood for 'Geometry and functions In 'N' Adaptions'.

The design team covered the Gina in a polyurethane-coated Spandex, which was tough, translucent, elastic, and impermeable. This concept car's interior apparatuses, like the steering wheel itself, sat inside the center console, only coming out when the car was started.

The Cadillac WTF is a pretty apt name for what is such a bonkers concept car. Short for World Thorium Fuel, Cadillac unveiled this concept in 2009, and it wasn't the battery or hydrogen-powered, but rather, nuclear-powered. Yes, you read that right. Another surprisingly ludicrous claim Cadillac made was that the WTF could achieve a 100-year maintenance-free lifespan!

Thorium is a radioactive material and was the supposed fuel behind the WTF concept. Making things even more ridiculous was that each wheel of the Cadillac WTF was made of six small wheels, each with its own motor. This meant that the Cadillac World Thorium Fuel actually had 24 wheels and 24 separate motors. By far one of the most surprising and insane concepts ever showcased, the Cadillac WTF naturally never came to fruition.

If it has wheels and an engine, Samarveer Singh is going to be obsessed with it. He is a budding Indian motorcycle racer, competing at the national level in his country in his very first year, chasing his dream around every corner of the racetrack. A touring enthusiast, Samarveer is forever stuck between the urge to constantly redline his bike, or save its clutch plates for longer.