A method and a system for automatic freewheeling of a vehicle, where in the vehicle is arranged a speed-lowering arrangement, including an engine, a wheel driven by the engine via an automated stage-geared gearbox, a gas pedal for regulating the driving torque of the engine, and a control unit. The control unit is arranged to, when the freewheel function is activated and in the presence of an input signal indicating that a predetermined vehicle speed limit is exceeded, to automatically deactivate the freewheel function and brake the vehicle with the speed lowering arrangement. The control unit is arranged to reactivate the freewheel function in the presence of an input signal indicating that the vehicle speed has fallen to close to the predetermined vehicle speed limit. The future progression of the vehicle may be simulated with a view to optimizing the freewheel function in terms of good fuel economy and/or increased comfort.