Suspicious car parked in my neighbourhood and what I did about it

Around 1:30am there was a car parked on my street across from my home that did not belong as my neighbours driveways were empty and there was no house on that side of the road. I went outside to investigate and saw that all the car lights were off but the engine was running. I shined by bright flashlight at the car and it did not move. I took my camera and took two pictures of the car and the person inside didn't move. I stood at the end of my driveway for about 6 minutes and the car did not do anything. Finally I approached the car and asked the person what he was doing parked in my neighbourhood and he said he was doing nothing illegal and went to show me his e-cigarette and said that this was all that he was doing. I said that him being parked with the engine running was unusual activity and that he needs to move along. He then proceeded to advise me that he was waiting for a friend down the street and advised me that he was going to go there right away and I could watch him go there. I watched the person drive 4 doors up and he parked in the driveway. I could not tell if he got out of the car but this person concerned me. I decided that I needed to get more involved and was thinking of what to do that could keep my neighbourhood safe. I decided that I was going to write to neighbourhood watch which ended up being sent to the police as a contact. I gave them the above reason why I was interested in starting up this task and you know what, they never even responded to me and it has been 4 days. I guess I should have mentioned that I would bring donuts and I would have gotten a surprise. If you like this please follow me.