The California Department of Motor Vehicles (DMV) issued permits allowing 29 self-driving vehicles to be tested on Californian freeways and neighborhoods with a human onboard incase the car malfunctions, CBS Sacramento News reported.

The driverless cars that navigate using sophisticated sensors and detailed maps had already been undergoing tests in California but only now has the DMV issued permits for the cars to go on freeways.

The self-driving cars include 25 of Google's Lexus SUVs, two Mercedes and two Volkswagens, according to the DMV. "A handful of other companies are applying for permits," DMV official Bernard Soriano said, CBS reported.

The issuing of permits came after California called for the DMV to regulate emerging technology in 2012. Following the 2012 bill, the DMV was required to identify the regulations necessary to ensure the safe operation of the autonomous cars on public roads no later than January 2015.

The DMV regulations published Tuesday state that the companies must carry an insurance of $5 million on each vehicle and must issue reports of any disengagement from its self-driving mode for whatever reason as well as renew the permit annually.

The total number of autonomous cars on United States roads is not known because states such as Nevada and Michigan do not require permits and manufacturer"s license plate suffice for experimental cars.

Meanwhile, the DMV announced in a press release that they are working on further regulations, to be issued by late December, which will apply once the cars are approved for the general public"s use.

In other news, the National Aeronautics and Space Administration (NASA), which has similar interests and expertise in the development of unmanned drones and systems, availed its Ames Research Center to Google for testing the driverless cars.

But the employees at the research center protested due to the risk involved in their participation.

"The union is prepared to take every lawful action necessary to prevent management from forcing Ames employees to be guinea pigs in an experiment against their will," Leland Stone, the Ames Center Employees Union president, wrote in an email to NASA employees late August, Mountain View Voice News reported.