Hot Wheels: Velocity X on Game Boy Advance tells the story of the evil MetaCog's attack on Hot Wheels HQ. He uses his hypnotic headlight to put the engineers to sleep and steal five cars and parts for a new prototype. The Professor, who is not affected by the hypnosis, modifies his robot Gear Head to become a top racer. With Gear Head, the player must beat MetaCog and his gang bosses to recapture the stolen parts and cars.
The game features various modes, including Story Mode with five worlds of seven missions each. The missions include races, stunt challenges, and objective-based tasks such as finding objects within a time limit or protecting another car. The final level in each world is a confrontation against one of the gang bosses, involving a race followed by a combat duel.
The gameplay takes place from an isometric perspective, with tracks featuring jumps, loops, and corkscrews where cars automatically move without falling off or failing to complete jumps. Power-ups such as weapons, shields, and repair kits are scattered around the tracks. Completing missions in Story Mode unlocks new cars and makes completed levels available for other modes.
The game includes additional modes like Race Mode with adjustable opponents and laps, Challenge mode with Battles and Tag varieties, and an in-game database of cars, characters, and power-ups that can be unlocked by progressing through the game. Game progress is saved via passwords, and connectivity to the GameCube version unlocks certain cars.