Energy management system for a motor vehicle, preferably an energy subsystem-overarching energy management system with a mixed form of centralized energy management and decentralized energy management, having: - a first autonomous energy subsystem, which requires energy to perform its function and comprises separate energy sub-management means and a separate energy storage means, - at least one second autonomous energy subsystem, which requires energy to perform its function and comprises separate energy sub-management means and a separate energy storage means, - an energy management means, which is used for higher level energy management of the first energy subsystem and of the second energy subsystem, - wherein the first energy subsystem is designed to transmit at least one item of management-related Information to the energy management means and the second energy subsystem is designed to transmit at least one item of management-related Information to the energy management means and the energy management means is designed to determine an operational requirement for the first energy subsystem depending on the management-related information (I1, I2) and to communicate the same to the first energy subsystem and to determine an operational requirement for the second energy subsystem depending on the management-related information (I1, I2) and to communicate the same to the second energy subsystem, wherein the management-related information of the first energy subsystem specifies an energy margin, by means of which the first energy subsystem can be operated functionally correctly, and the management-related information of the second energy subsystem specifies an energy margin, by means of which the second energy subsystem can be operated functionally correctly, and the operational requirement on the first energy subsystem comprises a power requirement ranging within the transmitted energy margin for the first energy subsystem and the operational requirement on the second energy subsystem comprises a power requirement ranging within the transmitted energy margin for the second energy subsystem. - a first autonomous energy subsystem, which requires energy to perform its function and comprises separate energy sub-management means and a separate energy storage means, - at least one second autonomous energy subsystem, which requires energy to perform its function and comprises separate energy sub-management means and a separate energy storage means, - an energy management means, which is used for higher level energy management of the first energy subsystem and of the second energy subsystem, - wherein the first energy subsystem is designed to transmit at least one item of management-related Information to the energy management means and the second energy subsystem is designed to transmit at least one item of management-related Information to the energy management means and the energy management means is designed to determine an operational requirement for the first energy subsystem depending on the management-related information (I1, I2) and to communicate the same to the first energy subsystem and to determine an operational requirement for the second energy subsystem depending on the management-related information (I1, I2) and to communicate the same to the second energy subsystem,