1. A method for providing a forward collision warning using a camera mountable in a motor vehicle, the method comprising: acquiring a plurality of image frames at known time intervals; selecting a patch in at least one of the image frames; tracking optical flow between the image frames of a plurality of image points of said patch; fitting the image points to at least one model; and based on the fit of the image points to said at least one model, determining a time-to-collision (TTC) if a collision is expected.