In Pixar’s Cars, the racing sponsor associated with the King and Doc Hudson is Dinoco.
Dinoco is one of the most prestigious brands in the Cars universe. The King, whose real name is Strip Weathers, drives a Dinoco-sponsored race car and is widely respected as a champion. Doc Hudson also raced for Dinoco during his earlier career, before an injury and an unfair loss of attention changed his life.
Lightning McQueen initially dreams of replacing the King as Dinoco’s sponsored driver. That ambition is one reason he is eager to win the Piston Cup. The Dinoco brand later becomes a recurring part of Pixar’s Cars stories and merchandise, often appearing alongside its blue dinosaur logo.
Rust-eze is the sponsor McQueen actually has at the beginning of the first film. It is a different company, known for its rusty-medicated-bumper-ointment branding, so the two sponsors should not be confused.