A power management system for an electrically driven vehicle, said vehicle comprising a powertrain of at least two electric motors that can be selectively geared into the powertrain by a respective clutch that is coupled to each of said at least two electric motors, and said power management system including an electric power source for powering the at least two electric motors, said power management system comprising a mechanical power demand indicator, said mechanical power demand indicator indicating a level of mechanical power demanded from the powertrain, and an electrical power demand estimator, that is arranged to estimate an electrical power demand of the electric motors as a function of the demanded mechanical power; wherein, the power management system is arranged to activate or deactivate one of said at least two electric motors in response to the mechanical power demand indicator, wherein the power management system is arranged to deactivate one of the at least two electric motors by mechanically gearing off from the powertrain when the power management system detects, - that the demanded mechanical power does not exceed a maximum value for the powertrain having one of said at least two electric motors deactivated; and - that the estimated electric power demanded by the powertrain having the one of said at least two electric motors deactivated, is lower than the estimated electric power demand by the powertrain having the one of said at least two electric motors activated; - or otherwise to activate the one of the electric motors. said vehicle comprising a powertrain of at least two electric motors that can be selectively geared into the powertrain by a respective clutch that is coupled to each of said at least two electric motors, and said power management system including an electric power source for powering the at least two electric motors, said power management system comprising a mechanical power demand indicator, said mechanical power demand indicator indicating a level of mechanical power demanded from the powertrain, and an electrical power demand estimator, that is arranged to estimate an electrical power demand of the electric motors as a function of the demanded mechanical power; wherein, the power management system is arranged to activate or deactivate one of said at least two electric motors in response to the mechanical power demand indicator, wherein the power management system is arranged to deactivate one of the at least two electric motors by mechanically gearing off from the powertrain when the power management system detects, - that the demanded mechanical power does not exceed a maximum value for the powertrain having one of said at least two electric motors deactivated; and - that the estimated electric power demanded by the powertrain having the one of said at least two electric motors deactivated, is lower than the estimated electric power demand by the powertrain having the one of said at least two electric motors activated; - or otherwise to activate the one of the electric motors. a mechanical power demand indicator, said mechanical power demand indicator indicating a level of mechanical power demanded from the powertrain, and an electrical power demand estimator, that is arranged to estimate an electrical power demand of the electric motors as a function of the demanded mechanical power; wherein, the power management system is arranged to activate or deactivate one of said at least two electric motors in response to the mechanical power demand indicator, wherein the power management system is arranged to deactivate one of the at least two electric motors by mechanically gearing off from the powertrain when the power management system detects, - that the demanded mechanical power does not exceed a maximum value for the powertrain having one of said at least two electric motors deactivated; and - that the estimated electric power demanded by the powertrain having the one of said at least two electric motors deactivated, is lower than the estimated electric power demand by the powertrain having the one of said at least two electric motors activated; - or otherwise to activate the one of the electric motors. - that the demanded mechanical power does not exceed a maximum value for the powertrain having one of said at least two electric motors deactivated; and - that the estimated electric power demanded by the powertrain having the one of said at least two electric motors deactivated, is lower than the estimated electric power demand by the powertrain having the one of said at least two electric motors activated; - or otherwise to activate the one of the electric motors.