Tim Kentley-Klay and Jesse Levinson. Zoox Zoox, the super-stealth self-driving-car startup, has closed a $200 million round of funding, according to a source familiar with its fundraising plans.

In an SEC filing on June 6, the startup said that it had raised over $100 million in equity. Business Insider has learned that the rest of the round has now closed. The Wall Street Journal first reported in May that an unspecified amount of funding gave it a $1 billion valuation.

Zoox has been working in secret on a fully autonomous car for years. In 2013, the company debuted some splashy renderings of the car, nicknamed "Boz," before reverting back into stealth mode. According to IEEE, the car is designed to not have windshields or a steering wheel or break pedal. Instead, it can drive in any direction while passengers sit inside, facing each other.

In March 2016, Zoox secured its permit to begin testing its self-driving car in California.

Zoox was founded by Tim Kentley-Klay, an Australian designer, and Jesse Levinson, a Stanford engineer who worked on self-driving cars with the co-creator of Google's self-driving car.