A flying car sketched on a Silicon Valley coffee shop napkin in 2015 made its public debut eight years later at the Detroit Auto Show, which concludes today.

Alef Aeronautics, a California-based start-up, unveiled its Model A prototype, to unusually large crowds that circled the curvy, UFO-like contraption, punctuated with a bubble-like compartment for two passengers. Alef is one of a half-dozen manufacturers in the U.S., Europe, and Asia planning to introduce flying cars in the next few years that are street-legal. The list also includes the Pal V Liberty, Samson Switchblade, Aska A5, Klein Vision AirCar, and Doroni H1.

Though the concept in Detroit showcased the Model A's exterior design, it did not drive, fly, or open to show the passenger cabin. "It's still not the final consumer version," Alef founder and CEO Jim Dukhovny told Robb Report during an interview after the press event. "But at this point, it's pretty close."

The Model A's blue underbody encases its four tires, each with an individual motor for the flying-car's drive mode. A silver, lightweight carbon-fiber mesh overlays its eight propellers, each with an independent, software-controlled electric propulsion system to spin at different speeds for redundancy and control.

"You need airflow so obviously we cannot have a solid top, but we can't have it completely open for safety reasons," says Dukhovny, whose father was famous musician and poet Leonid Dukhovny.

The conveyance measures about 17 feet long, seven feet wide and six feet high – similar to the dimensions of an SUV—designed to fit in any parking space or garage.

Dukhovny says the tri-modal machine—which can drive, take off vertically, and fly forward—can travel 200 miles on the road and 110 miles in flight.