I first saw this technique in an article by George Lepp. He was photographing a baboon running across a stream but I decided the technique could be applied to anything moving, such as a car. I live near Mulholland drive in Southern California and lots of fancy cars are driven up and down its curves and grades. While riding a bicycle up it I noticed this spot with a good view of the curve below, went out there later that week, and set up on tripod and made nine images. They are blended together in successive layers using PSCC. If you try this be sure you use M mode. It will probably take you several tries to get the the distances between cars (or whatever) an amount that is aesthetically pleasing.

Canon 6D, 24-70 F4.0 at 59mm, 1/1000, ISO 400, F8.0, nine images