"The cars have a number of sensors, such as cameras, lasers and radar, to monitor road conditions and improve the technology," said Chris Gaither, a Google spokesman in an email to Computerworld. "For our testing purposes, the cars log data about their performance -- how fast they're going, where they are, where they detect obstacles, etc. -- as well as data from the equipment on the car."

Gaither noted that he could not say what, if any, data would continue to be collected from the cars once testing is over and they are being sold commercially. "It would be premature to speculate," he added.

The letter was sent to Assembly Speaker John A. Perez, who has not replied to a request for comment.

According to Gaither, Google's driverless cars have logged more than 200,000 miles so far.

Last month, looking for partners in the company's efforts to develop the vehicles. Anthony Levandowski, head of Google's self-driving car project, told an audience there that the company would like to get such cars on the road within the next decade.