In Pixar's Cars, Rust-eze is the sponsor whose logo appears on Lightning McQueen's racing body.
Rust-eze is a fictional medicated-bumper-ointment company, and its sponsorship is central to McQueen's early career. He dislikes the brand's rusty visual image and dreams of replacing it with the prestigious Dinoco team after the Piston Cup tiebreaker.
The Rust-eze brothers, Rusty and Dusty, own the company and support McQueen even when his attitude is difficult. Their sponsorship also gives the film one of its recurring visual jokes: the champion racer is covered in advertising for a product associated with rust removal.
Dinoco is a separate fictional sponsor associated with The King and later with McQueen under different circumstances. Octane Gain and Vitoline are other Piston Cup sponsors, but neither is McQueen's original sponsor.