Spritle Racer (三船くりお, Mifune Kurio) is Speed's younger brother and the shows main source of comic relief. He and his pet chimpanzee, Chim Chim are an inseparable team. They have a way of popping up at just the right time to pull Speed out of a jam so that he can go on to save the day.
Spritle, together with his pet chimpanzee - who responded to the name of Chim Chim in the American version (Sanpei in the Japanese original) - have the disconcerting habit of sneaking inside the Mach 5's trunk. Their rebellious attitudes often lead them to trouble and are often in Speed's way, their mischief often aids Speed away from danger however. The pint-sized pair is able to challenge and overcome muscle-bound thugs or gun-toting gangsters using slingshots, small rocks, and food as weapons. Yet, oftentimes, in an attempt to prove themselves to the family, they will try to solve a mystery on their own. Of course, their efforts often make matters worse.
Spritle and Chim-Chim dress in identical jumpsuits and striped hats and often perform identical physical actions. They both have an extreme appetite for candy and they are usually bribed with dessert or other presents. These two love candy so much, that they fight between themselves over whatever bribes they manage to collect. Spritle and Chim-Chim often use a slingshot to combat any threats that come to both themselves and/or Speed.
According to Peter Fernandez's introduction in the American release of the Mach GoGoGo manga, Spritle got his name for being an energetic "sprite."
- Spritle is seven years old until The Royal Race Part 2.
- Spritle has, on at least one occasion, driven the Mach 5, implying that he can drive cars.
- His underwear is white and green striped.
- The cartoon Dexter's Laboratory has a Speed Racer parody episode, "Mock 5". In it, the main character Dexter's older sister Dee Dee portrays both Spritle and Racer X.