What was the title of the first Pixar short film starring characters from the Cars universe?

Mater and the Ghostlight was the first Pixar short film starring characters from the Cars universe.

The short was released in 2006 as a companion to Cars. It focuses on Mater, the tow truck from Radiator Springs, who enjoys playing pranks on the other residents. The townspeople decide to frighten him with a ghost story about the Ghostlight, creating a humorous lesson about the consequences of his behavior.

Mater and the Ghostlight expands the original film’s setting without changing its central characters or visual style. It was included with home-video releases of Cars and helped establish a pattern of short projects connected to the franchise.

Later Cars-related shorts include Tokyo Mater, Rescue Squad Mater, and Unidentified Flying Mater. Those titles are sometimes confused with the first short because they also center on Mater. Mater and the Ghostlight is distinct because its story takes place in Radiator Springs and uses the supernatural-looking Ghostlight as its main comic device.