Forget self-driving cars, Google’s co-founder is spending big bucks to develop flying cars. It turns out that Larry Page is personally funding two separate startups focused on making personal air travel a reality.

Page’s efforts began back in 2010 when he helped launch Zee.Aero, a small firm based right near Google headquarters. The secretive startup quickly drew attention for a patent detailing a small plane that lands and takes off vertically (pictured above). Bloomberg reports that Page has been secretly funding Zee the entire time (spending over $100 million in the process), along with a second smaller company called Kitty Hawk located about a half-mile away.

For a while, Page even used the second floor of Zee’s offices as a personal apartment, decorated with one of the first SpaceX rocket engines. Employees referred to him as GUS (which stood for “guy upstairs”) before eventually expanding to fill the second floor. The firm now employs almost 150 people and also uses a nearby airport hangar.

Zee’s current prototypes apparently feature a narrow frame, a cockpit with room for one passenger and several propellers, giving it the look of a small airplane. It’s also extremely loud, according to people working at the airport where it’s being tested. Kitty Hawk’s model allegedly looks more like a massive drone with four propellers.

Flying cars may still sound like a fantasy, but they may not be that far from actually hitting the market. Thanks to breakthroughs in self-driving software and improved materials, these futuristic vehicles could arrive in as little as 5-10 years, thanks in part to Larry Page and his commitment to the crazy technology.