Traffic flow dynamics are closely related to traffic flow stability and specifically the growth/dissipation pattern of disturbances.However, the traffic theories have been controversial due to a lack of precise traffic data.We have studied traffic flow from a new perspective by carrying out large-scale car-following experiment on an open road section,which overcomes the intrinsic deficiency of empirical observations.The experiment has shown clearly the nature of car-following, which runs against the traditional traffic flow theory.Simulations show that by removing the fundamental notion in the traditional car-following models and allowing the traffic state to span a two-dimensional region in velocity-spacing plane, the growth pattern of disturbances has changed qualitatively and becomes qualitatively or even quantitatively in consistent with that observed in the experiment.