Vehicles in Mario Kart 8 Deluxe are fairly complicated. Once you set aside the character and the way they affect the handling, 3 factors determine how the vehicle moves. These include the kart/bike, wheels, and glider.
Introduced in Mario Kart 7, the glider and wheels became new options for customizability. This was most likely added in Mario Kart 7 to make up for the game's lacluster amount of characters due to its small storage size as a 3DS game. Certain players have found the best combinations to beat records. In most cases however, any player can beat the Nin☆ time trials as long as they are good enough at the game.