In Pixar's Cars, Seligman, Arizona, inspired the setting of Radiator Springs.
Seligman is a historic community on former U.S. Route 66. Pixar artists and filmmakers studied Route 66 towns while developing the film, and Seligman became an important model for Radiator Springs and its roadside atmosphere. The town's preservation history helped connect the fictional story to the real decline and revival of the famous highway.
Radiator Springs is presented as a once-busy desert stop bypassed by a newer interstate. That plot reflects the experience of many Route 66 communities after modern highways redirected long-distance traffic. The film turns this historical pattern into the central setting for Lightning McQueen's change in attitude.
Other Arizona Route 66 places, including Kingman and Williams, are also associated with the highway and can be mistaken for the direct answer. Seligman is the specific town most often identified as the key inspiration.