The idea for an animated film about cars was first discussed between director John Lasseter and character designer Bob Pauley as early as 1993 while carpooling during the production of Toy Story.

Story artist Jorgen Klubien initially developed a script called The Yellow Car, about an electric car living in a gas-guzzling world, inspired by The Ugly Duckling and the poor reception of the Mini-El car in his native Denmark.

Lasseter got the idea for the film's story after taking a 2000 cross-country road trip with his wife and five sons, after which he contacted Route 66 historian Michael Wallis, who led eleven Pixar animators on research road trips in rented white Cadillacs.

The film's working title was Route 66, but it was changed to Cars to avoid confusion with the 1960s Route 66 television series.

Lightning McQueen's racing number was originally meant to be 57, a reference to Lasseter's birth year 1957, but was changed to 95 as a reference to 1995, the release year of Toy Story.

The film was dedicated to co-writer Joe Ranft, who died in a car crash during production; it was the second Pixar film dedicated to his memory after Corpse Bride, and it featured his final two voice roles, Red and Jerry Recycled Batteries.

Cars was Paul Newman's last non-documentary film role before his retirement in 2007 and death in 2008.

Unlike most anthropomorphic car designs, the characters' eyes were placed on the windshield rather than in the headlights, a deliberate choice by Lasseter to make the cars feel more human-like rather than snake-like.

To create realistic metallic reflections for the car characters, Pixar's technical team added a ray-tracing capability to their existing Renderman rendering program, a first for the studio.

The computers used to develop the film were four times faster than those used for The Incredibles and 1,000 times faster than those used for Toy Story.

The soundtrack includes two versions of the classic Bobby Troup jazz standard 'Route 66,' one by Chuck Berry and a new version recorded specifically for the film's credits by John Mayer.

Cars has been noted to mirror the plot of the 1991 film Doc Hollywood, in which a young doctor is sentenced to work in a small town after causing an accident and comes to appreciate small-town values.

Cars was the final film independently produced by Pixar before its acquisition by Disney was completed in January 2006.