Automated vehicle technology is advancing rapidly. But some automakers fret the public and regulators aren’t ready yet. Technology that will allow cars to operate with minimal input from human drivers is being demonstrated more openly by a few automakers, notably Audi, Toyota’s Lexus and Mercedes-Benz. The technology will be available in a few years, they say.

Automakers worry, however, that consumers and regulators may balk at giving up control. Drivers increasingly use anti-lock brakes, stability control, adaptive cruise control, lane departure warnings and other high-tech gadgetry. Most don’t realize it’s a small step to a nearly fully automatic control system, carmakers say.

“You put all these thing together and already the car is helping to drive itself,” says Scott Keogh, president of Audi AG’s U.S. subsidiary. At the Consumer Electronics Show in Las Vegas this week Audi showed a prototype of “Traffic Jam Assist” for use in traffic traveling below 60 kilometers (37 miles) per hour.

Optical and radar sensors identify lane markers to keep the specially equipped Audi A6 from drifting out of its lane, nudging the wheel in the direction it must go. Forward sensors slow the car down when it gets too close to a vehicle ahead, or speeds it up when the gap is large. The sensors and the chips that process information are getting smaller, cheaper and more powerful at a dramatic pace.

Audi is the second company, and first automaker after Google , to receive permission to test its systems on Nevada roads. Other major automakers, including General Motors Co. and Ford Motor Co. , are working on autonomous systems but sidestepped making any announcements or holding briefings at the show.

Keogh and other Audi executives and engineers from Germany declined to say exactly when “Traffic Jam Assist” might be available in an Audi model — except to say “this decade.” They were quick to point out that while the technology could relieve the monotony and improve safety in stop-and-go driving, the driver “must not” relinquish control entirely. The sneak peek at the technologies is designed, executives said, to familiarize a public that might otherwise find them strange or frightening.

Unlike Google, which it testing a driverless Toyota Prius it developed for on California and Nevada roads toward a future of driverless cars, Audi rejects the notion that drivers might one day become obsolete.

Well, almost. Audi also demonstrated a self-parking car at a Las Vegas parking garage that found its own space and returned at the summons of its “driver.” “Audi can provide the technology and some public relations to show the value,” says Wolfgang Durheimer, Audi board member in charge of research and development. “The key” for consumer acceptance is to show “that it solves a problem consumers have.”

Durheimer said advanced Audi systems could find their first widespread consumer acceptance in urban Japan, where a shortage of parking and congestion provide an opening. Durheimer and other Audi executives tried to avoid using the word “autonomous” in regard to its technology, because of the implication that the driver isn’t needed. “This technology isn’t developed over night, it needs a lot of testing, here on the roads of Nevada,” and elsewhere, he said.

Audi prefers an incremental approach to adding technology “layers” of control so consumers and regulators can become acclimated to each new feature without becoming overwhelmed. Audi’s first lane departure warning system, for example, was improved so that the car’s steering can be set to intervene in the case of departure rather than just sound a warning.

Brad Stertz, an Audi spokesman, said U.S. regulatory officials and insurers will have to clarify their stance on features that take control of the car in certain circumstances: “What might happen if an accident does take place? Who is responsible?”