CNET

If you spot a Lexus SUV driving itself to your favorite Austin barbecue joint, don't panic. Google's self-driving car has arrived in Texas.

In a Google+ post Tuesday, Google announced that it has picked Austin as the next location for its self-driving vehicle tests. To rev up the project, one of the company's Lexus SUVs is already driving around a few square miles north and northeast of downtown Austin -- with a backup driver behind the wheel for good measure.

Austin marks the second testbed for Google's robo-cars . The company has already been driving around the streets of Mountain View, Calif., with its fleet of modified Lexus RX450h cars and Toyota Prius models. But expanding the program to another city is important at this point as the cars need to learn how to navigate the different roads, driving conditions and challenges offered in other locales.

So just how have the cars been faring without a driver?

In May, Google released a report on its self-driving car project, revealing that over the course of six years and more than 1.8 million miles of autonomous and manual driving, its cars have been involved in 12 minor accidents. In all of those cases, according to Google, a human being driving the other car was the cause of the accident rather than one of Google's robo-cars -- and no injuries occurred. Still, that opens up the thorny issue of how Google's cars can learn to share the road with human drivers, who may be more apt to make mistakes than the self-driving cars themselves.

Google has acknowledged the challenges involved when man meets machine.

"Even when our software and sensors can detect a sticky situation and take action earlier and faster than an alert human driver, sometimes we won't be able to overcome the realities of speed and distance; sometimes we'll get hit just waiting for a light to change," Chris Urmson, director of the company's self-driving car program, said in a blog post in May. "And that's important context for communities with self-driving cars on their streets; although we wish we could avoid all accidents, some will be unavoidable."

What, if anything, has Google been doing to try to avoid accidents caused by other cars?

"Our sensors give us 360-degree visibility around the vehicle at all times, out to a distance of nearly two football fields, and the vehicle never gets distracted," a Google spokeswoman said. "We've also baked-in defensive driving behavior: We do things to avoid getting into a tricky situation in the first place -- e.g. staying out of other drivers' blind spots, nudging away from lane-splitting motorcycles or wobbling vehicles, pausing 1.5 seconds before proceeding into an intersection after a red light turns green, etc. It still amazes us how many times people have rear-ended us while we've been completely stopped at a stoplight for several seconds."

So far, the backup or -- as Google calls them -- safety drivers in the prototype cars have had a steering wheel, accelerator pedal and brake pedal that allows them to take control if needed. The speed of the cars have been capped at 25 miles per hour. But what happens when the cars don't have a backup driver and start driving at normal speed limits? That prospect is still a number of years away, which is why testing the cars in different cities and different scenarios is crucial.

"It's important for us to get experience testing our software in different driving environments, traffic patterns and road conditions -- so we're ready to take on Austin's pedicabs, pickup trucks and everything in between," Google said in its post. "Keep it weird for us, Austin, and visit our website to let us know how we're driving."

A second self-driving Lexus will arrive in Austin later this week, the spokeswoman said.

Since the self-driving project got off the ground in 2009, most of Google's testing has taken place in its home base of Mountain View. Now the company not only wants to work with driving conditions elsewhere but also "learn how different communities perceive and interact with self-driving vehicles, and that can vary in different parts of the country," the spokeswoman added.

Beyond Google, major automakers such as Ford, Audi and Nissan have all been experimenting with self-driving cars. In March, Carlos Ghosn, CEO of the Nissan-Renault Alliance, said he expects autonomous-driving to have three phases: a first wave emerging in 2016, followed by self-driving cars that navigate a highway by 2018 and then cars that can negotiate city driving by 2020. That same month, Elon Musk, CEO of electric-car maker Tesla Motors, said he expects self-driving cars to be the norm within 20 years.

Self-driving cars may still be a rare sight on the roads as they've typically been restricted to testing facilities under controlled conditions. But they are coming, sooner or later. If Google and the automakers can hammer out the challenges of navigating the roads, self-driving cars could potentially save some of the more than 1 million people killed each year in car accidents worldwide.