From the Super Mario Wiki
The Circuit Special is an unlockable kart body in Mario Kart 8. The kart resembles a Formula One car with exhaust pipes below the spoiler, more specifically the ones seen in F-1 Race, another Nintendo game on the NES and Game Boy. It also looks similar to the Sprinter from Mario Kart Wii. In fact, its Dutch name is the Sprinter 2.0, making it a successor to the Sprinter and the B Dasher, which is called Sprinter in Dutch. Its Russian name also means Sprinter when transliterated to English. The emblem is located on the hood.
Mario Kart 8/Mario Kart 8 Deluxe
It offers a speed and weight boost, but it hinders in acceleration and especially traction; it shares its stats with the Sports Coupe, Mach 8, B Dasher, P-Wing, and Gold Standard. It shares the same sound with the Sports Coupe and is one of the few vehicles in the game to have a supercharged engine, along with the aforementioned karts.
In Mario Kart 8 Deluxe, it is now available from the start. CPU Bowser, Wario, Roy, and King Boo occasionally use this body during races, with Bowser using the Monster tires, and King Boo using the Standard tires, respectively. Pink Gold Peach uses the body with the Sponge tires instead. CPU Lemmy and Luigi are also seen using this kart body, with Lemmy using the Standard tires and Luigi using the Slick tires with the MKTV Parafoil instead. The Circuit Special now only shares stats with the B Dasher and the P-Wing, boosting speed and weight while lowering acceleration, handling, and traction.
Mario Kart Tour
The Circuit Special returns in Mario Kart Tour, where it is classified as a High-End kart. Slipstreaming lasts longer and yields more points while using this kart. It uses the Slick tires from Mario Kart 8 and Mario Kart 8 Deluxe. Unlike before, the kart's varnish does not change depending on the character using it, as it always uses the blue and white varnish. This is due to the fact that the black, purple, and yellow varnish is instead used by a variant of the kart called the Black Circuit, which is also classified as a High-End kart.
The Circuit Special has four different varnish colors. They are similar to the Sport Bike.
Mario Kart 8
Mario Kart 8 Deluxe
Mario Kart Tour
Names in other languages