The car choreography involved a lot of combat as well as stunt-like scenes, called "Car Fu." 

According to Digital Domain's Kim Libreri, who heads the new technology efforts, Sparky was a necessity because of all the photographic bubbles that had to be integrated. "We wanted to make sure that David [Tattersall] had as good a feedback [in realtime] to know what these characters were going to go into while he was lighting and just to make sure that the key to fill ratios matched the backgrounds and colors. What would happen is that Dennis Martin would go out and shoot them, Lubo would paint them and that would be the bubble for the character. So what we did was take a games-level Intel PC, popped an NVIDIA 8800 GPU into it and then bought a Blackmagic DeckLink high-def capture card, put the whole thing together, our engineer Brian Smith spent six weeks writing software, and that was Sparky."

The CG vehicle design and racing infrastructure were also put together by Digital Domain, along with a couple of the major track races: the hometown Thunderhead contests and the climactic Grand Prix; CafeFX did the Fuji Lexicon race and a combination of BUF and Sony Pictures Imageworks executed three major sequences, including the cross country rally called the Casa Cristo 5000. All of actual racing action took place in a small cockpit that sat on a motion base and then they either uploaded files into the motion base or played live with the gimbal operator moving the gimbal per instructions by the Wachowskis. The CG car shells went through an extensive design phase for more than a year. There were dozens of custom cars but came up with a concept to have track racing vehicles rotate all four wheels 180 degrees in either direction, which they called the "T 180," so effectively they could do a four-wheel rotation. That enabled the cars to get into choreographed martial arts action, or Car Fu. And they threw in the jump jacks from the TV series, which could be controlled independently, and they could perform aerial acrobatics in these vehicles, speeding at 200-300 mph. The tracks were closer to a skateboard park than a Formula One circuit.

"We very much used previs as the first stage of animation set up," Glass adds, "and in many cases getting us most of the way down the animation pipe. We did a lot of conceptual tests for how the other material would work in terms of the way layers might move and shift behind people.

"We used a lot of off-the-shelf software. We knew we were going to use many vendors and wanted the previs scenes to be as useful as possible. The basis was Maya, and, although the rigs could be considered proprietary [they were a custom component that worked in Maya], Digital Domain allowed us to implement them in our scenes and also to offer them to other vendors. Digital Domain rendered in mental ray and did a lot of work building custom shaders in collaboration with mental images for the cars and the paint work to produce stunning-looking vehicles.

"On the composite side, Digital Domain and some old colleagues of ours built some custom kernels for doing focus filters, which became quite a motif throughout the film. One of our initial observations was that earlier animation sometimes has a primitive defocus filter and everything has the same level of defocus because it is a flat plane beyond the foreground characters. If you seriously crank the defocus level, it really pops the characters from their backgrounds. Introduce different shapes -- a circle or a hexagon or the shape of an iris and diamonds and rectangles and chevrons and hearts -- and the emotion or message in a scene was sometimes reflected in the way the image defocuses. The particle pipeline was Houdini based in conjunction with Maya and rendered through mental ray.