As the co-founder of search giant Google and the CEO of its holding company, Alphabet, Larry Page has overseen projects involving driverless cars, smart contact lenses, and solar-powered drones that beam a high-speed internet connection to people below. And now, he's reportedly spent $100 million funding another ambitious project outside the reigns of Alphabet.

A recent story by Bloomberg Businessweek reveals that Page has been secretly funding two companies that are trying to build flying cars for several years. According to Bloomberg's Ashlee Vance and Brad Stone, this is "just one part of Page's plan to usher in an age of personalized air travel, free from gridlocked streets and the cramped indignities of modern flight."

The companies are named Zee.Aero and Kitty Hawk. Zee.Aero has been the subject of much speculation in Silicon Valley after it opened an office next to Google's headquarters in Mountain View, California, three years ago. The company refused to speak to the press, but one reporter spotted a patent filing that indicated the company was working on an electric-powered flying car. 

Bloomberg  says that 10 people familiar with the matter say that Page has "personally funded" Zee.Aero since it launched in 2010, and assisted the company in keeping it shrouded in secrecy. Zee.Aero's original office consisted of two levels--one level for Zee.Aero employees, and another that served as Page's "man cave." Employees only referred to Page as GUS--the guy upstairs.

Now, Zee.Aero has moved into a new office space in Hollister, California--right across the street from the headquarters of another flying car operation called Kitty Hawk that Page is also reportedly funding. Kitty Hawk has another Google connection--its president is listed as Sebastian Thrun, who founded the company's research division, Google X, in 2010. 

Although driverless cars are all the rage in Silicon Valley right now, inventors have wanted to build Jetsons-style flying cars for years. According to Bloomberg, the world's premier flying car enthusiast is 79-year-old Paul Moller, who tested his first prototype for a flying car in 1966.

But Page's pet projects appear might have more promise. As navigation systems become more and more precise, and the software needed to power driverless cars becomes better at detecting and distinguishing between objects, flying cars may yet have their moment.