The nation's first stretch of automated highway debuted in San Diego recently, providing a glimpse of hands-off commuting in the next century. Cars equipped with magnets, radar and 1-in. video cameras on the rear-view mirrors followed visual aids along the road to keep the cars in line as they made their way in an orderly procession along a 7.5-mile stretch of Interstate 15. The demonstration was part of an initial project sponsored by the National Automated Highway System Consortium, a group of private and public agencies and universities. Cars equipped with magnets, radar and 1-in. video cameras on the rear-view mirrors followed visual aids along the road to keep the cars in line.