"And we got the attention of the Google founders. Yeah. So Larry came to the race itself and … came disguised with, like, a hat and sunglasses so he wouldn't be bothered by everybody. But … he had a keen interest in this. Larry has been a believer in this technology for much longer than I even knew. And so was Sergey. And they really want to understand what's going on."

"My team turned out to be the lucky winner for whatever reason," Thrun told CNBC in an interview for the new series "The Brave Ones" .

Thrun had built a self-driving car to compete in the DARPA Grand Challenge – a 132 mile off-road course through mountain roads in California. The Stanford Racing Team with their vehicle named Stanley came first.

And it began with Google founders Larry Page and Sergey Brin turning up to the race in a disguise.

In 2005, Sebastian Thrun was busy building a driverless car at Stanford to prepare for a race that would eventually lead to him being hired by Google to head up their most ambitious "moonshot" projects.

In 2007, Thrun then built the next version of his driverless cars which had cameras on them, allowing it to record 360 degrees of video. This sparked off the start of a well-known feature on Google Maps known as Street View.

"And we went to Google and said we'd love to help you build Street View. And we kind of ended up … felt like an acquisition of a little start-up company, kind of Stanford transitioning into Google where me and four of my grad students then became Street View enthusiasts. And we built up Street View and with a singular vision to photograph every street in the world," Thrun said.

Three years later in 2010, Google X – the tech giant's lab that created its Waymo self-driving car program and the augmented reality Google Glass device – was set up by Thrun, Yoky Matsuoka, and Astro Teller.

The aim of the lab was to develop "moonshots" – inventions that could be big in the future. Waymo was spun out of Google X in September and is now Google's driverless car division. At the U.S. search giant, Google X was a big secret.

"We started Google X – with the self-driving car project. And the idea was to really kind of build an innovation center that has authority to just do crazy things," Thrun told CNBC.

"We had a separate building that no one knew about. At least for a year and a half no one in Google had a clue we existed."

'Just do it'

Thrun wasn't even convinced that the self-driving car project he began at Google would be safe in public. Page then challenged Thrun to make it work and drew up a 1,000 mile route in California that was very tricky to drive.

"Look, it can be done. People can do it. Just do it," Page told Thrun, according to the Google X co-founder. "And to my complete surprise, blows my mind, about 15 months later a team of 12 engineers did it."

Waymo's autonomous vehicles have now driven 2.5 million miles and the company is looking to partner with established automakers.

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