NEW YORK (CNN/Money) - General Motors Corp. unveiled a drivable version of its vision of automotive design of the future Wednesday, as it presented a car without an engine compartment that allows the driver to sit in different positions throughout the car.

The world's largest automaker's new concept car is a fuel cell-powered vehicle that puts both the fuel cells and the vehicle's powertrain in a relatively flat platform running below the car body. The platform ranged from 11 inches thick to seven inches thick on the sides, with the four wheels attached to it, making it look something like an overgrown skateboard.

GM's new Hy-wire concept car does not have an engine compartment.

The design freedom that comes from having a nearly flat powertrain allowed GM to experiment with using a "drive-by-wire" system that eliminates the steering column and foot pedals now standard on all vehicles. It allows the steering wheel to be shifted easily between the seats, and provides much greater room and visibility for the driver and passengers because of the lack of a traditional engine compartment.

GM unveiled this vision of future auto designs at the North American International Auto Show in January, but the version of the vehicle it used that day -- called the AUTOnomy -- wasn't actually able to drive. The new concept car, dubbed the Hy-wire, can be driven.

"The fact that we developed Hy-wire as a drivable concept vehicle in just eight months shows our commitment to this technology and the speed at which we are progressing," GM CEO Rick Wagoner said.

An actual production version of the vehicle still is many years away. The fuel cell, which converts hydrogen into power and produces only water vapor as a waste product, is not yet economically viable. And the skateboard-like platform still needs many refinements, GM design executives admitted. The AUTOnomy, which was not burdened by the need to actually be drivable, showed GM's concept of a platform that is only about six inches thick, rather than the 11- to 7-inch thick dimensions of the Hy-wire.

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"The new packaging of the components was a major challenge and certainly, in terms of compactness, we're not at the finish line yet," said Erhard Schubert, director of the GM research facility in Germany that produced Hy-wire.

GM believes one major advantage of this design concept is that it could allow mass production of the skateboard for different models of the car, reducing manufacturing costs.

GM will put the Hy-wire on public display for the first time at the Paris Motor Show Sept. 26.