We’re accelerating toward a future of self-driving cars faster than anyone expected. It was only two years ago that Google revealed it had surreptitiously logged more than 200,000 miles with a fleet of self-driving Toyota Priuses. That was right before Audi paraded a self-driving TT up Pikes Peak in Colorado.

Now the federal government is getting involved. Last week, the National Highway Traffic Safety Administration laid out its first plans to test and regulate the technology. At a meeting in Washington, D.C., NHTSA administrator David Strickland said developing regulations for self-driving cars will be like nothing else the agency has ever seen.

“Most of NHTSA’s safety standards assume the need for a human driver to operate required safety equipment,” he said. “A vehicle that drives itself challenges this basic assumption.” Autonomous cars will also be a challenge for the legal community to sort out liability issues, and perhaps for drivers to accept the technology.

Strickland acknowledged that “NHTSA has been having extensive discussions with Google” as well as with U.S. automakers regarding plans to make self-driving cars available. GM has said it expects to have fully autonomous cars available by 2020; Google hasn't revealed its commercial plans beyond signaling a willingness to work with automakers.

He also said NHTSA has developed a "motor-vehicle automation road map." As evidence of how far into the future that road map extends, Strickland detailed the agency’s vision of the evolution of autonomous driving, which includes three stages:

• Monitored automation, which “involves shared authority: The driver cedes primary control, but is still responsible for monitoring and safe operation.” An example that will be available in just a few years is Cadillac’s Super Cruise system, which combines a lane-centering feature with adaptive cruise control, leading to what Strickland called “hands-off" and "feet-off driving," but is still "eyes-on" driving in which “the driver must continually monitor the road and traffic.” Volvo also unveiled a similar technology last week.

• Conditionally automated, in which “the driver can cede full control authority under certain traffic and environmental conditions but is expected to be available for occasional control.” Google’s self-driving technology is one example. “Here it’s ‘hands-off,’ ‘feet-off’ and ‘eyes-off’ until the driver or the vehicle decides that it’s time for the driver to resume control,” Strickland said.

• Fully automated, in which “responsibility for safe operation rests solely on the automated systems.” He added that there’s “no such vehicle being designed for civilian highway use at this time, but at some time in the future this may be the logical outcome of the many efforts at automation currently under way."

To better understand the implications of self-driving technology -- and how to draft regulations for it -- NHTSA is planning a a multiyear, $1.75 million research project that it will conduct with Virginia Tech to study the real-world effects of self-driving technology. The agency sees automated driving as a supplement to the vehicle-to-vehicle communication research it is conducting in a yearlong field test in Ann Arbor, Mich.

Strickland didn't mention two factors that most experts say will delay any adoption of self-driving cars: legal issues and consumer acceptance. While he did say that determining fault in a crash "may be much more difficult when control of a vehicle seamlessly transitions from the driver to the vehicle," it will likely take years of legal wrangling to sort out liability with self-driving cars.

I'm confident that consumer acceptance will come much more quickly -- similar to a century before when the then-new "horseless carriage" was looked at with the same suspicion and skepticism as self-driving cars are now.

Doug Newcomb has been covering car technology for more than 20 years for outlets ranging from Rolling Stone to Edmunds.com. In 2008, he published his first book, "Car Audio for Dummies" (Wiley). He lives and drives in Hood River, Ore., with his wife and two kids, who share his passion for cars and car technology, especially driving and listening to music.