An arrangement for determining a vehicle speed behaviour model for a leading vehicle, where the leading vehicle drives along a path in front of a trailing host vehicle and where the determination is done by a control unit in the host vehicle, where the host vehicle includes an arrangement for measuring the time gap to the leading vehicle, an arrangement for measuring the speed of the host vehicle, an arrangement for obtaining external information regarding an upcoming change in a road condition, where the control unit is adapted for monitoring the change in vehicle speed of the leading vehicle, and for determining a vehicle speed behaviour model for the leading vehicle based on the monitored change in vehicle speed of the leading vehicle. The vehicle speed behaviour of a leading vehicle can be used by the host vehicle to optimize the fuel consumption, the comfort and the safety of the host vehicle.
