Before 1968 cruiser control was basically a jumped up mechincal fuel injectors. After 1968 intergrated computers were used so the car could actually compute how to keep a steady speed without buring fuel and brakes. It has been rather unchanged for the last couple of decades. The most important part about the cruiser control computer is it's central location in the car. It has been used as a jumping off point for further interration in cars. Modern models can use radar sensors to keep the cars distane for cars infrount of it.