An on-vehicle system for assessing efficiency of an operator of a vehicle at least substantially real time, the system comprising: a plurality of sensors configured to measure or detect conditions of components of the vehicle, and convert the detected conditions into analog or digital information; an audiovisual display device; a processor; and a data storage storing program instructions, the analog or digital information from the sensors, and other data; wherein the program instructions, when executed by the processor, (i) control the on-vehicle system to determine a state of the vehicle within a vehicle's environment based on the analog or digital information from the sensors and to determine, within a current time frame, a desired behavior of the operator based on the determined state of the vehicle, (ii) determine that, within the current time frame, an actual behavior of the operator from a predetermined set of behaviors has occurred based on the determined state of the vehicle, (iii) assess performance of the operator within the current time frame, based on a difference between the determined desired behavior of the operator and the determined actual behavior of the operator; and (iv) present the operator, via the audiovisual display device, cueing based on the assessment in at least substantially real-time; wherein the predetermined set of behaviors includes at least one of running auxiliary equipment, excessive idle, progressive shifting, speeding, hard-braking, hard-acceleration, and unsafe maneuver; and wherein the desired behavior of the operator is determined by the system based on the current situation, including the driver's behavior, the state of the vehicle, the vehicle's load and the environmental conditions. a plurality of sensors configured to measure or detect conditions of components of the vehicle, and convert the detected conditions into analog or digital information; an audiovisual display device; a processor; and a data storage storing program instructions, the analog or digital information from the sensors, and other data; wherein the program instructions, when executed by the processor, (i) control the on-vehicle system to determine a state of the vehicle within a vehicle's environment based on the analog or digital information from the sensors and to determine, within a current time frame, a desired behavior of the operator based on the determined state of the vehicle, (ii) determine that, within the current time frame, an actual behavior of the operator from a predetermined set of behaviors has occurred based on the determined state of the vehicle, (iii) assess performance of the operator within the current time frame, based on a difference between the determined desired behavior of the operator and the determined actual behavior of the operator; and (iv) present the operator, via the audiovisual display device, cueing based on the assessment in at least substantially real-time; wherein the predetermined set of behaviors includes at least one of running auxiliary equipment, excessive idle, progressive shifting, speeding, hard-braking, hard-acceleration, and unsafe maneuver; and wherein the desired behavior of the operator is determined by the system based on the current situation, including the driver's behavior, the state of the vehicle, the vehicle's load and the environmental conditions.