Most content in Blur is tied to "Rival Demands" and career progression rather than manual codes.
Since the game is no longer officially supported, many PC players use trainers from sites like Cheat Happens to instantly unlock all cars or opponents. These tools allow you to toggle "Super Fan Status," which bypasses standard progression requirements. Blur Cheats, Codes, and Secrets for PC - GameFAQs blur pc unlock codes 2021 updated