During a recent test of a Volkswagen GTD on the autobahn near Berlin, I set the adaptive cruise control and turned on the lane departure warning system. Then, at nearly 100 mph, I took my hands off the steering wheel.
The bright red diesel-powered hatchback meandered slightly to the right until the tires were just about touching the painted lane divider. Then the car automatically steered itself into the center of the lane.
A few minutes later, I did nothing with my feet as the GTD approached a slower car in the same lane. Automatically, the VW slowed itself and maintained a safe distance.
This was the first time I got a sense of the promise of automated driving. To me, there is no doubt the technology has the potential to improve vehicle safety. It works.
Many of the building blocks that enable cars to drive themselves are already on the vehicle, such as electric steering, sensors at the wheels or in the steering system that determine speed and direction of travel, cameras, and or radar or lidar [an acronym for "light detection and ranging"] systems that can see 360 degrees around the vehicle.
But massive engineering challenges remain.
Despite last week's boast by Nissan Executive Vice President Andy Palmer that automated driving technology will be ready for the market by 2020, the industry is likely years, if not decades, away from people being able to get in a car, type an address into the nav screen and have the vehicle automatically take them there while they read the newspaper.
The engineering and software challenge -- and it is a big one -- is getting many high-tech components to work seamlessly and safely all of the time, in all weather conditions and all driving situations. There must also be a robust warning system that lets the driver known when it's time to take the wheel.
Perfecting automated driving is a top initiative at German supplier Robert Bosch GmbH. The company says it is technically possible, but today's components need further development.
Wolf-Henning Scheider, who oversees Bosch's automotive group, told Automotive News this year that he thinks fully automated driving is years away. Even then it will only be functional in certain situations, he says.
"Generally, the automatic driving functions will come step by step," he said. "The ultimate end of that is very difficult to see. Certainly it is foreseeable that we will have an exit-to-exit highway driving that is automatic.
"Fully automatic city driving is the most complex situation, much more complex than any airplane autopilot. But it should be the ultimate target."
Bosch believes vehicles will need to know where they are before "100 percent safety 100 percent of the time" can be ensured. Real-time geographic and traffic data that lets the car's computers see the road ahead will, for instance, ensure speed is reduced before a vehicle reaches a sharp curve or approaches a construction zone. The car must know where it is so the driver can be prompted to take over in a situation where the car may not be able to drive itself, such through a long, dark tunnel.
Technology isn't the only wild card.
Government safety regulators around the world will also have a major impact on the roll out of automated driving.
If today's patchwork of global safety and emissions regulations are any indication, then there will likely be a different set of rules for automated driving in each region, further complicating engineering and software development of the systems.
In the United States, the patchwork has already emerged. At least three states -- Florida, California and Nevada -- have passed laws allowing driverless cars. But in the majority of states, the driver must be in control behind the wheel.
Automakers and suppliers have tested self-driving cars on closed courses. Google now has more than 300,000 test miles in real-world driving on its small fleet of driverless cars. So the technology is maturing quickly. But putting it on the road at prices people can afford and getting it to work perfectly in millions of cars will be tough.
There's also the question of how much consumers value automated driving technology. Lexus was first on the market in 2006 with a vehicle that could park itself, the LS 460.
But Lexus quietly dropped the Advanced Parking Guidance System at the start of the 2013 model year. The reason: lack of demand.