Adaptive cruise control offers glimpse into safer future for cars.

Byline: Lawrence Ulrich

DETROIT _ Pressing a button on the Mercedes S-Class or new Lexus LS 430 offers the first glimpse of an automotive future in which vehicles will sense and respond to the often hazardous world around them.

The luxury sedans' adaptive cruise control is a baby step toward a day when cars might use combinations of radar, video, computers and satellites to avoid collisions, navigate and maintain course, respond to road signs or even drive themselves while drivers nap.

Automotive experts dubbed the concept "the electronic cocoon" at the Convergence 2000 automotive electronics congress that ended Wednesday at Detroit's Cobo Center. The idea is to swaddle automobiles in a layer of electronics to protect occupants during driving and before and after crashes.

The systems could save lives, ease traffic congestion and make driving far less hectic and dangerous, experts say.

Already in the United States, Mercedes' adaptive cruise control shoots radar waves from the front bumper to vehicles ahead, allowing the car to maintain a set distance behind a vehicle in its lane.

The Lexus uses a laser beam as the basis for its optional system, accelerating, slowing or lightly braking …