i read somewhere that schizophrenics and narcissists are the two most important groups of stalkers - schizophrenics because they make the victim part of their delusions and narcissists for revenge/control purposes.
so the aim of his actions is to get a handle on your emotions, creep you out, make you think about him, anything. i agree wiht the above person that as long as he doesn't give any signs of doing more than just lurking around, you shouldn't do anything because any reaction is a sign of control and at this stage will rather provoke him. the real battle is in your head: Try to not care or at least act as if you don't. if nothing happens he will get bored and look for other sources of supply. but, obviously, there are limits to what you should put up with...
i once met a person whom i assume to be a narcissist who went through a cycle of idealization - devaluation - creepy stalking with me. after he had devalued me he suddenly came on to me again and i was creeped - how could he think this would work, does he think i don't have a memory? he's crazy! and my discomfort was visible so that's what he went for, lurking around, showing up funny places, also sometimes smiling, sometimes stone-faced. it wasn't very extreme but i tend to mentally obsess about stuff so after 4 days i became insomniac worrying about this.
i got very angry, didn't want him to play such an important role in my life. i overthought the situation. he is extremely intelligent and still the most subtle and creative manipulator i have met, but he appeared to have limits when it comes to being violent/physically forceful. so i could rate the situation as not actually dangerous and decided to not give him what he wanted, the creep reaction. so next time he showed up i just beamed at him sheepishly and waved. he was baffled. from then on, i adopted the sheep policy, like i was too dumb to even realize he's playing games. stalkign stopped instantaneously.
now don't take this as a typical example - maybe it was so easy because i was just a side project in his plot for world domination (i was). also the best way of implementing "i don't care" may vary between different people - i am an extrovert and a bit narcissistic myself, so adopting a particular emotional policy seemed reasonable but you really need the emotional self-control to stick with it despite his best efforts to break it down. for others, maybe not reacting at all will be easier and more effective. but the bottom line is that as long as bad things only happen in your head and not in real life, your real struggle is for control about your emotions.
so think for a moment about your reaction to his appearances - what will he see? you freezing, looking terrified? that makes it worth driving all across town! any form of interaction with him, any ambivalence inside you will feed him. if he is still looking for pretexts (like exercising) that indicates that his attempts are still bound by trying to appear normal - so i wouldn't assume he's dangerous for the moment. so don't react to his provocations. should he, however, actually use or threaten violence that's a whole different story.