1. A method for cruise control of a harvester, comprising steps of: monitoring certain operating conditions of the harvester representative of torque demand on an engine of the harvester, while controlling a speed of the engine and operating systems of the harvester; determining a value representative of a predicted torque demand on the engine as a function of the monitored conditions; setting the speed of the engine at a value so as to produce an outputted torque sufficient to meet the predicted torque demand; and automatically varying a propulsion speed of the harvester as required to substantially continuously equalize the torque demand to the outputted torque; and monitoring a harvesting system of the harvester to determine if the harvesting system is in a harvesting mode, and, if no, then ceasing the step of automatically varying the propulsion speed.