Apple is on track to begin testing self-driving cars in California.

The tech giant was added to a long list of companies on the California Department of Motor Vehicles website that hold permits for the state's Autonomous Vehicle Tester Program.

Apple, traditionally highly secretive about its technology, joins companies like Google, Tesla, Ford, Mercedes-Benz and others, that are testing autonomous driving technology.

Apple's permit allows it to test three 2015 Lexus SUVs vehicles retrofitted with self-driving technology, and covers six human operators, who must be in the SUV during testing, according to Fox Business.

The company has been highly secretive about its autonomous driving program, called Project Titan, and is not commenting on the new permit.