This paper presents a driver assistance system designed to minimize the effect of driver reaction time on lane and speed maintenance operations. Nearly-instantaneous correcting actions are provided through a hierarchical arrangement of behaviors, by avoiding the time lag associated with deliberative or planning steps found in many control algorithms. Concepts originating in the field of robotics, including artificial potential fields and behavior-based systems, are interpreted for application to automotive control, where vehicle dynamics places considerable practical constraints on implementation. Ideas found in the study of emergent behavior in nature provide continuous, non-stepwise control signals, suitable for additive corrective inputs at highway velocities.This approach is effective for a substantial subset of road automobiles operating over a variety of speeds. A practical method for setting control parameters is found through optimization methods, corroborated with physically-driven metrics and then demonstrated. Simulation results and an analysis of system stability, using a reduced-order model, suggest that controller corrections are consistent and predictable-prompting its incorporation into a larger vehicle safety system which includes vehicle-to-vehicle (V2V) components.