1. A method for vehicle detection and tracking, comprising: acquiring video data including a plurality of frames; comparing a first frame of the acquired video data against a set of one or more vehicle detectors to form vehicle hypotheses; pruning and verifying the vehicle hypotheses using a set of course-to-fine constraints to detect a vehicle; and tracking the detected vehicle within one or more subsequent frames of the acquired video data by fusing shape template matching with one or more vehicle detectors.