California has given three automobile manufacturers a total of 29 permits to test driverless cars on public roads.

The three companies that received the permits are Google, Volkswagen AG for Audi and Daimler AG for Mercedes-Benz.

The issuance of permits comes in the wake of news that testing driverless cars will require permits in California starting Sept. 16. In the past, previous testers of driverless tech were allowed to carry out their experiments without the need of permits.

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Methods that "teach" driverless cars how to drive safely are currently being developed and tested in Germany by the engineers at Mercedes-Benz.

The automobile firm said its test drivers "must recognize clearly when the car is in autonomous driving mode and must be able to override this mode at any time; in addition, the car must be capable of stopping autonomously at any time."

Other firms are applying for the same permits to test their own vehicles. The requirements for these permits state that human operators should be present in the vehicle and will be able to override the car's computer in case of an emergency.

"Audi is a driving force behind the research taking automated driving from science fiction to pre-production readiness," said Scott Keogh Audi America president. "Obtaining the first permit issued by the state of California shows that we intend to remain the leader in this vital technology frontier."

Keogh's company was also the first car manufacturer to get permits in Nevada, which it received in 2012.

Other car companies currently developing their own autonomous vehicles are Ford, General Motors, Nissan and Toyota.

TagsDriverless Cars, cars, mercedes benz, Toyota, Permit, california, Nevada, volkswagen, Google driverless cars, car