This exact thing happened in my old apartment complex that was in what I consider to be the ghetto. I did a fair bit of research on it, and from what I gathered, thugs will rob people who confronts them at gun point.

With that said, I had a decent view of the car that was going off from my window, so one night I turned all my lights off and set up my high powered rifle scope, cracked the bottom of my blinds a couple inches, and observed the traffic nearby the car for an hour of so. I noticed only one man go near the car, some words were exchanged with someone in the car, and he left. The old man seemed innocent enough. The alarm persisted though. Everyone else stayed away. Seems they got the same bad vibe as I did.

I did notice that the car would drive forward and backwards every so often so it would get louder and quieter (and likely louder for others farther away) every so often. On occasion, this black car would have the alarm shut off, and just sit there.

I got a very bad vibe from it much like you do. I do not consider myself paranoid, and I am not ignorant of possible dangers. I did get the feeling it was a cross between a test to see who the threats in the neighborhood were to potential burglaring plans etc., though. It didn't feel like the whole intention of it was to rob someone. There was definitely another motive behind it.

My best advice to you op, is to move as soon as you can since it sounds like you live in a similar neighborhood as I did. I realize money can be tight, and even for me it still is after moving, but I found a couple hundred bucks a month increase in rent (which I originally didn't think I could afford) gets me a very nice complex, that is miles away from da hood. I now have a much better peace of mind knowing that mostly smart criminals live here (think, getting your mail stolen), and not the ones that will rob me at gun point in broad daylight. This incident wouldn't fly in richer neighborhoods.