There certainly are people who act as though they have no soul. Your analogy of the car driving into a wall fits perfectly with someone who is acting as though they have no soul. They figuratively "crash" into whichever vice or sinful activity it is they are pursuing.
I have to disagree with your statement that "we", the decision making part of our being, is soul, though. I think if the soul were responsible for making all our decisions then we'd be living in a perfect world. This is the separation I am interested in mostly. The body clearly makes many decisions that either "starve or feed" the soul. I don't think the decision itself is made by the soul. I think the body can allow the soul's input into the decision, and an enlightened person hears the soul's recommendations loudest over any earthly desires, but I don't think the soul can override the body without the body allowing it. I think this is the essence of free will. Ideally, we are training our bodies to respond like souls would. Kind of like the soul is the teacher of the body. The student can do as he or she wishes, but a good student listens to the teacher and heeds his advice.