Technology giant Google has begun lobbying to legalise self-driving cars in the US state of Nevada after trials in neighbouring California.

Cars equiped with special cameras, used to photograph whole streets, can be seen on the Google street-view stand at the world's biggest high-tech fair, the CeBIT on March 3, 2010.
Google's new self-drive cars could look something like their street-view vehicles
The internet and computer software company has been testing the vehicles for the past year and have now hired a lobbyist to promote their cause.
Las Vegas-based David Goldwater has already started highlighting the benefits of the self-driving cars, according to the New York Times.
Google believes the vehicles will prove to be safer, more fuel-efficient and environmentally friendly than human-driven cars.
Our goal is to help prevent traffic accidents, free up people's time and reduce carbon emissions.
Google engineer Sebastian Thrun
In prototype vehicles Google used laser range-finders mounted on the roof and video cameras to detect traffic, along with detailed maps to find their way from point-to-point.
A statement from Google read: "We have developed technology for cars that can drive themselves. We think this is a first in robotics research.
"This is all made possible by Google’s data centers, which can process the enormous amounts of information gathered by our cars when mapping their terrain."
Last year the company controversially travelled 140,000 miles across California to test the self-driving cars and was encouraged by its findings.
Specially-adapted Toyota Priuses drove from Google's Mountain View headquarters in northern California and down the scenic Pacific Coast highway to Santa Monica.
They crossed the Golden Gate Bridge and drove down San Francisco's Lombard Street - among the steepest and curviest roads in the world.
The cars remained manned at all times by a trained driver ready to take control, as well as by a software expert.
The ultimate aim, Google insists, is that the cars will eventually help reduce road traffic and cut the number of accidents.
The only thing human 'drivers' are required to do is programme their destination and the car calculates the route and drives itself there.
Google are lobbying for two amendments to the current road law in Nevada.
The first includes an electric-vehicle bill, which would permit testing of autonomous vehicles.
Automobiles wait in a traffic jam on a New York City highway
Google believes their vehicles will also help reduce traffic
It addition it is looking for an exemption that would allow texting in a car.
Google researchers insist the artificial intelligence technology could eventually halve the 1.2 million lives lost every year on roads around the world.
The cars are programmed to stay within the speed limit - the maximum for every road is included in its database.
Google engineer Sebastian Thrun said: "Our goal is to help prevent traffic accidents, free up people's time and reduce carbon emissions by fundamentally changing car use.
"Our automated cars use video cameras, radar sensors and a laser range finder to 'see' other traffic, as well as detailed maps which we collect using manually driven vehicles to navigate the road ahead."
The German-born engineer added: "Safety has been our first priority in this project. Our cars are never unmanned.
"We always have a trained safety driver behind the wheel who can take over as easily as one disengages cruise control."