Rust-eze sponsors Lightning McQueen's racing team in Pixar's Cars.
Rust-eze is a fictional automotive product company whose branding is displayed on McQueen at the start of the film. The business is associated with a rusty-car treatment, which creates a deliberately comic contrast with McQueen's ambition to become a prestigious champion.
Rusty and Dusty Rust-eze are the company's owners and McQueen's sponsors. Their support helps launch his racing career, even though McQueen initially looks down on the brand and its image. The sponsorship becomes part of his character arc as he learns to value people who supported him before he was famous.
Dinoco is a different fictional sponsor in the Cars universe. It is connected with The King and later becomes a major aspiration for McQueen, making it an easy answer to confuse with Rust-eze. The Piston Cup itself is the franchise's fictional championship trophy.