This paper describes fundamental path tracking control performance characteristics for curvilinear motion based on the nonlinear dynamics. Curvilinear motion is ubiquitous to many human behaviors and engineering applications. The results provide essential insights about vehicle control requirements, aerial and ground robots, as well as for understanding human guidance and control skills. The paper describes the theoretical analysis and illustrates the fundamental properties through simulations and follows with two examples based on empirical data. The first example is based on the design specifications for different alpine skiing disciplines. The second example is based on results from closed-loop identification of a miniature helicopter path tracking experiment under both human and automatic control. The results validate the path tracking adaptation strategy suggested by analysis and demonstrate the general significance of the results.