Toad drafting in Mario Kart Wii.
Drafting (sometimes known as slipstreaming) is a technique in Mario Kart 64, Mario Kart DS, Mario Kart Wii, Mario Kart 7, Mario Kart 8, and Mario Kart 8 Deluxe that allows for a short speed boost. In its first iteration in MK64, drafting is more subtle: there are no lines to indicate if it's being done correctly, the wind is gray instead of blue, and the speed boost is brief. In the following two games, when trailing behind another racer, blue lines appear around the player's kart or bike. If the position is held for about 3-5 seconds, the player will be surrounded in a blue wind with a modest speed increase. The boost lasts for about 3 seconds, or until the player hits a wall, obstacle, racer, or item. It can last as long as a Mushroom boost.
While tricky to do on curves, this is incredibly useful on straightaways. However, it can be a risky maneuver - racers looking to receive a speed boost can be easily flipped over by held items. It's better to use this on lower-leveled CPUs than real racers, although it could decide the first lap if used at the very beginning. Drafting was originally going to be absent from Mario Kart 8, but was implemented in the final version of the game.