Which Pixar short features Mater traveling back in time to the Old West?

The Pixar short featuring Mater traveling back in time to the Old West is Time Travel Mater.

Time Travel Mater is part of the Cars Toons series, a collection of animated shorts centered on Mater and Lightning McQueen. In this installment, Mater’s story involves time travel and a western-style setting, allowing the character to encounter an earlier era of the Cars world.

The short was released in 2012 and is one of the Mater’s Tall Tales episodes. These stories are built around Mater’s enthusiastic, often improbable accounts of his past adventures. The comedy comes from the contrast between Mater’s certainty and the increasingly extraordinary situations he describes.

The title is sometimes confused with other Cars Toons names, including Air Mater, Heavy Metal Mater, and Mater Private Eye. Those shorts place Mater in different genres and situations, but none is the time-traveling Old West episode.