OpenCV provides the Haar cascade face detector that uses some Haar classification algorithms to quickly find patterns in images.

All the cool phones now are doing facial recognition. While that sounds like a big job, you can add face detection and recognition easily to your projects if you can support the OpenCV library.

Some research led me to a Haar classifier. It sounds like I need a file of negative images (the empty road) and a file of images with cars in them including coordinates of where the car is.