David is giving a persuasive speech, that menas he is trying to convince or persuade his audience to do or don't do something. In this case, he probably wants to stop people from driving after drinking alcohol. To accomplish his objective, he is recurring to anecdotal evidence. That is, evidence taken out of real life events that support the author's point of view, he tells it as a short story emphasizing on the most important things that will help him make his point. By doing this, the audience can relate this events to their lifes, feeling empathic, knowing that this accidents can happen to anyone, therefore taking action in order to avoid them. We can see David is appealing to pathos, or emotions, to make a deeper impact.
