To make streaking car light shots you need to shoot at night, or use dark filters, and set your camera on a tripod. I usually try for say 10 seconds to one minute, depending on the light and how many cars there are. I have taken slow shutter photos from overpasses, where you get streaks of light along the road, but this time I wanted to get a low angle, so the streaking lights would appear to be hovering in the air. Trying to find a spot with skyscrapers in the background, car lights in the foreground (preferably more tail lights as headlights tend to blow out the whites too much) and where I could get my tripod down on the street level was tricky. At one point, I actually set up my tripod in the road, which was OK until a taxi decided to pull in next to me and almost took out my camera. I didn't quite get the effect I was after, but these four photos were kind of nice. Anyway, I will keep trying.