V
I am concerned and negative about you and this situation. Don't smile or notice him, don't give him any cause or hope.
I honestly would look him straight in the eye with a look of severe disapproval and ask what his problem was. If he's innocent, he'll just drive off disappointed. If he's a predator, hopefully he'll be discouraged and drive off. Listen: If the guy has half a brain he should know that a stranger stopping his car in the street to chat it up with a lady he doesn't know is going to cause concern to you. If wisdom escapes him on that point alone, he's a knucklehead.
We don't want to live in fear of people, but we also don't want to be a victim. There is a lot of information online on avoiding predators and safety tips. I hope you check it out, dear.