The street race to develop and test autonomous vehicles ramped up this week when the California Department of Motor Vehicles granted Apple Inc. a license to test three driverless SUVs on state roads.

Apple, long secretive about its interest and activity in the autonomous vehicle space, isn't talking about what it plans for the three Lexus RX450h models and six drivers now permitted by the DMV.

In comments responding to guidance for driverless cars released by the National Highway Transportation Safety Administration's in November, Steve Kenner, Apple's director of product integrity, said the company is “investing heavily in the study of machine learning and automation, and is excited about the potential of automated systems in many areas, including transportation.”