In 2006, supervising animator on the film Scott Clark, spoke about the challenges of animating car characters, saying: "Getting a full range of performance and emotion from these characters and making them still seem like cars was a tough assignment, but that's what animation does best. You use your imagination, and you make the movements and gestures fit with the design. Our car characters may not have arms and legs, but we can lean the tires in or out to suggest hands opening up or closing in. We can use steering to point a certain direction. We also designed a special eyelid and an eyebrow for the windshield that lets us communicate an expressiveness that cars don't have." Doug Sweetland, who also served as supervising animator, also spoke about the challenges, saying: "It took a different kind of animator to really be able to interpret the "Cars" models, than it did to interpret something like "The Incredibles" models. With "The Incredibles", the animator could get reference for the characters by shooting himself and watching the footage. But with "Cars", it departs completely from any reference. Yes they're cars, but no car can do what our characters do. It's pure fantasy. It took a lot of trial and error to get them to look right."