First Step Toward Automated Cars?: ANN ARBOR, Mich. –– Most Americans haven't heard of adaptive cruise control--not yet, anyway. But carmakers expect the newfangled speed-and-braking system to become as common on cars as anti-lock brakes and ordinary cruise control. Cars with adaptive cruise control (ACC) are outfitted with a pair of infrared sensors on the front bumper. One sensor gauges the distance to the nearest car directly in front, adjusting its tracking sweep whenever the road becomes curvy. The other sensor detects lane-changing cars by sizing up what's happening on either side. (The second sensor is calibrated to ignore stationary objects such as signs.) When a driver turns on ACC, he or she sets a target speed and a following distance. The ACC system maintains that speed and distance by accelerating and downshifting based on what the sensors report back. (Future versions will add braking authority.) When the road is free of cars, the system works just like old-fashioned cruise control. Once other cars materialize, the car slows to keep the proper distance.