This paper deals with characteristics of driver responses in large disturbances. 10-vehicle platoons are employed in the car-following experiments which was held on the test track. The characteristics of driver responses are used for the propagating time of speed disturbances, the relationships between speed and headway of followers, and the followers' trajectories on the speed-platoon length plane. Some characteristics including dynamic behaviors of followers are clearly recognized by using the relationships between followers' speed and platoon length. The results of this study can be appplicable for basic informations making a model of car-following behaviors at the bottlenecks on the inter-city freeways.