The tech guru behind Google's self-driving cars just left after seven and a half years

The tech lead of Google's self-driving car project is leaving the company after more than seven years.

CTO Chris Urmson announced his departure on Medium: "Now, 1.8 million miles of autonomous driving later, I've decided the time is right to step down and find my next adventure."

Though it started as a secret project within Google in 2009, the self-driving car team is now housed in X, the "moonshot" lab of parent company Alphabet.

The division hired John Krafcik as its CEO last fall.

This is the latest in a string of departures from the unit, Recode points out, highlighting that one of the project's other cofounders, Jiajun Zhu, recently left for an unnamed startup, while another group, including cofounder Anthony Levandowski, went to found a self-driving truck startup at the beginning of the year.

From a team spokesperson:

"Seven years ago, the idea that a car could drive itself wasn't much more than an idea. Chris has been a vital force for the project, helping the team move from a research phase to a point where this life-saving technology will soon become a reality. He departs with our warmest wishes."