Joby Aviation, the secretive aviation startup, announced today that it raised $100 million from a variety of investors, including the venture capital arms of Intel, Toyota, and JetBlue. The money will help in the development of the company’s air taxi prototype, which, according to a report in Bloomberg, has been conducting test flights at Joby’s private airfield in Northern California.

Joby is the brainchild of inventor JoeBen Bevirt, who started the company in 2009. Bevirt told the Santa Cruz Sentinel that he plans to hire 100 additional engineers to his team of 120 employees in order to design and build a functioning air taxi vehicle. Unlike the dozens of other companies that are currently building electric vertical take-off and landing (eVTOL) aircraft, Joby has kept much of its project under wraps.

“This is an entirely new vehicle.”

The few renderings that are out there show a plane-drone hybrid with 12 rotors and room in the cabin for four passengers, though a spokesperson cautioned that what Joby is working on now is “entirely new.” The company wouldn’t provide any recent photographs or images of its prototype aircraft. Bloomberg was granted access to Joby’s test facility on the condition its reporter refrained from describing the vehicle in detail:

The pilot managed a vertical takeoff, 15 minutes of flight in a 15-mile loop, and a safe landing. Powered by electric motors and sophisticated control software, the taxi performs like a cross between a drone and a small plane, able to zip straight up on takeoff and then fly at twice the speed of a helicopter while making about as much noise as a swarm of superbees.

Joby isn’t the only company in pursuit of a Jetsons-esque dream of “flying cars.” At least 19 companies are developing air taxi plans, including legacy manufacturers like Boeing and Airbus, big tech firms like Uber, and small startups like Kitty Hawk, owned by Google founder Larry Page. Geely, the parent company of Volvo, recently acquired an aviation startup called Terrafugia. Intel and Daimler are investors in the German company Volocopter.

Of course, many companies — Joby included — have promised revolutionary new aircraft for years, only to miss deadlines or fail to live up to past promises. The jury is still out on whether an eVTOL-based air taxi system would make an appreciable contribution to a next-generation transportation system, or whether it would simply be an escape hatch for the super rich to avoid street-level congestion.