Join the BLR Unofficial Fans Roblox group and like the game (required for redeeming codes). Launch Blue Lock Rivals on Roblox. Reach Player Level 10 (required for redeeming codes).

One example is the Chevrolet Corvette StingRay Racer Concepte '59. Once you have the car, do a single race in Arcade Mode and win. You can even set the difficulty down.