There is no CG in this video and yet it messes with reality so much that it sure seems like it's complete make believe. Instead, Cy Kuckenbaker simply removed and reorganized cars of the same color to make it seem as if they were driving together in a group. It's a hypnotizing effect to see cars of the same color driving as one fleet.
The source footage for the video was taken over a 4-minute shot in the afternoon from the Washington Street bridge above State Route 163 in San Diego. All the cars you see in the video above are actually real cars that drove by, they're just in different bunches now.
Kuckenbaker wanted to see the color preferences of car drivers in San Diego but I think the video is also fascinating because of its artificial rhythm. Here's the full video: