Sometime back, before the HOV lanes were opened in San Diego, there was experimenting with autonomous cars. At the time, the study was to learn how traffic could be reduced with self-driving cars. The picture I remember seeing, was that of about seven cars, traveling train-like and controlled by sensors on each car; much like the anticollision sensors we have today.
An autonomous car has been proven viable, according to this article from The San Diego Tribune.
"Back in 1995, the NavLab 5 team at Carnegie Mellon University launched an autonomous vehicle on a trip from Pittsburgh to San Diego.
The vehicle navigated itself, without intervention from a human driver, for 98 percent of the 2,800 mile journey. It averaged speeds above 60 mph."
http://www.sandiegouniontribune.com/...330-story.html