For the past seven years the annual Los Angeles Auto Show has held a themed challenge, where auto designers are asked to create their vision of what future cars will look like. Last year, the challenge focused on the technology savvy youth. This year's challenge was all about minimizing consumption of the earth's resources.

Competitors were asked to design an energy efficient, light-weight (no more than 1,000lbs) four passenger vehicle, without compromising any of the comfort features.

Seven automakers took up the '1000-Pound Car of the Future' challenge and the results, as you will see, are some pretty snazzy, extremely energy efficient cars - which may never see the light of day, but are sure cool to imagine.

Honda Air

This radical design was inspired by the modern roller coaster and skydiving wing suits. Thanks to a hub-less wheel and drive system, glass reinforced seating panel, tires made from urethane and very minimal sub-frame components, the weight was kept below 800lbs. In keeping with the green theme, the car also features vegetable based polymer panels and is powered by a compressed air and pneumatic regulator system.

Maybach DRS by Mercedes, Japan

Mercedes Benz's Japanese studio, a first time entrant to the challenge designed what is essentially a rickshaw of the future. Powered by an electric drive and controlled by a computer that is plugged into a big city's transport infrastructure, the electric car can also be pedaled using human power should the driver feel inclined to exercise.

Mazda MX-0

Mazda's entry was a high torque electric car - that was developed with three criteria in mind - zero weight, zero carbon emission and zero mass. To do this, they redesigned each of the components of the Mx-5, by either reducing the parts or replacing them with lightweight materials.

Mercedes Benz Biome

The US division of Mercedes Benz came up with a real sci-fi version for their concept car - One where customer's specific desires are genetically engineered into the star, which then combines with a seed capsule and grows into a car. The solar powered car is also designed to release pure oxygen as it purrs along the highways - A little far-fetched even for the future don't you think?

Nissan IV concept

Nissan had a similar idea - Using organic synthetics they envision a revolutionary manufacturing technique, whereby automotive parts are cultivated like plants. They even featured an interwoven organic frame that was grown from fast-growing ivy and re-enforced with a spider silk composite - Nice imagination, but is it really possible? We don't know.

Toyota Nori

Toyota's Nori was more down to earth - Their vision was to build a car wherein the body and its chassis are one streamlined unit making it stronger, lighter and more attractive to look at. In line with the green theme, Nori would harness the sun's energy through solar cells that are built into its body.

Volvo Air Motion Canyon Carver

Volvo's concept of a light functional car was a clam shell made from ultra light carbon fiber. The car will also require much fewer components than a traditional car, thanks to its powerful, compressed air motors, that substitute the normal heavy internal combustion engine. Similar to some of the other cars, the designers integrated the chassis, interior and suspension, lowering the weight of the car even further.

The Winner Of The 1000 Pound Car Of The Future Is . .

Cadillac Aera

While the cars were all impressive, it was the simple elegance of General Motor's Cadillac Aera, which combined art and science that impressed the judges most. The 1000lbs 4-person vehicle that could travel 1000 miles before requiring refueling, was conceived from a highly advanced 3D lattice mono-formed frame. Weight was again kept in check with ultra-lightweight materials and like most of the concept cars it was powered by an air compression system.

Each year, the concept cars look even more futuristic and the ideas behind them are quite radical - Will we ever get to such clean energy cars? Who knows, but its sure fun to envision them isn't it?

Sources: topspeed.com, laautoshow.com,cardesignnews.com