The motivation of this paper is to propose a simple and reliable method to identify on-road vehicle events, particularly in the driving situations. A content rhythm is extracted by applying a virtual line lies on the same position of each frame. Thereupon a simplified representation of a continuous video is to record the temporal information of vehicle status. Thus, vehicle situations such as lane changing, vehicle passing, safe distance and zigzag driving can be detected instantly by analyzing the statistical characteristics of content rhythm. The proposed method can not only prevent accidents but also improve the traffic safety by monitoring the on-road vehicle status. Experimental results show the proposed method is reliable for vehicle event detection.