A method for choosing a transmission mode in a vehicle over the course of a road section, wherein a lowest permitted speed v min, which an actual speed for said vehicle should exceed, is defined for said road section; the method comprising: - simulation of at least one future speed profile v sim for an actual speed for said vehicle over the course of said road section, in which said simulation is conducted when said road section lies ahead of said vehicle and in which said simulation of each of said at least one future speed profile v sim is based on a road slope and on a transmission mode for said vehicle; - evaluation of an applicability for a transmission mode, wherein said transmission mode for the respective said at least one future speed profile v sim is deemed applicable if the respective said at least one future speed profile v sim is greater than said lowest permitted speed v min throughout a first time period T 12, which extends from a first moment T 1, when said at least one simulation is conducted, to a second, later moment T 2, wherein said second moment T 2 constitutes a moment such that said first time period T 12 corresponds to a smallest permitted time period for which a transmission mode should be utilized after said simulation; and - utilization of said evaluation in said choice of a transmission mode, wherein - said evaluated transmission mode comprises coasting of said vehicle; and - said evaluation comprises a comparison of said at least one future speed profile v sim with a highest permitted speed v max, below which an actual speed for said vehicle should be kept characterized in that - said at least one future speed profile v sim comprises a simulated future speed profile v sim_coast related to coasting; and - said evaluation comprises a comparison of a simulated future speed profile v sim_HighGear related to a highest possible gear position for a gearbox in said vehicle with said highest permitted speed v max; and - coasting is deemed applicable if said future speed profile v sim_HighGear related to a highest possible gear position is less than said highest permitted speed v max throughout a second time period T 13, in which said second time period T 13 is longer than said first time period T 12 and extends from said first moment T 1 to a third moment T 3, when said future speed profile v sim_coast related to coasting falls below said lowest permitted speed v min. - simulation of at least one future speed profile v sim for an actual speed for said vehicle over the course of said road section, in which said simulation is conducted when said road section lies ahead of said vehicle and in which said simulation of each of said at least one future speed profile v sim is based on a road slope and on a transmission mode for said vehicle; - evaluation of an applicability for a transmission mode, wherein said transmission mode for the respective said at least one future speed profile v sim is deemed applicable if the respective said at least one future speed profile v sim is greater than said lowest permitted speed v min throughout a first time period T 12, which extends from a first moment T 1, when said at least one simulation is conducted, to a second, later moment T 2, wherein said second moment T 2 constitutes a moment such that said first time period T 12 corresponds to a smallest permitted time period for which a transmission mode should be utilized after said simulation; and - utilization of said evaluation in said choice of a transmission mode, wherein - said evaluated transmission mode comprises coasting of said vehicle; and - said evaluation comprises a comparison of said at least one future speed profile v sim with a highest permitted speed v max, below which an actual speed for said vehicle should be kept - said at least one future speed profile v sim comprises a simulated future speed profile v sim_coast related to coasting; and - said evaluation comprises a comparison of a simulated future speed profile v sim_HighGear related to a highest possible gear position for a gearbox in said vehicle with said highest permitted speed v max; and - coasting is deemed applicable if said future speed profile v sim_HighGear related to a highest possible gear position is less than said highest permitted speed v max throughout a second time period T 13, in which said second time period T 13 is longer than said first time period T 12 and extends from said first moment T 1 to a third moment T 3, when said future speed profile v sim_coast related to coasting falls below said lowest permitted speed v min.