This is just a neat trick to bring a little life into urban night matte paintings. I think this highlights how things can be way over thought and often the more simple solution is often the more elegant one. So if it ever comes up "how are we going to do cars." and their solution is "let's get our high res cars in there and light them, and do a overnight render." You can say "there is a better way!"
This car is just made up of images of light put onto cards, tail lights, head lights, light on the ground and a car shaped matte object to occlude the light on the cards.
I made the cards and the car matte shape in Maya. I UVed the car pieces in patches (offset UVs like you would do for Mari). I did this so I could have multiple textures applied to one obj in nuke.
In Nuke I used the tool I created "Nuke/MARI Bridge: Multi UDIM Gadget" that allows Nuke to apply multiple textures to a multi patched UVed obj. Then in Nuke it is an easy thing to animate cars driving around.
I would recommend that you animate a transform node and not on the obj node. If you do that you can move translate the obj around and it will not mess up your animation.