Slipstream

Slipstreaming (also known as Drafting) is a technique in Mario Kart DS and Mario Kart Wii. If a player trails behind a player for so long, a Ghostline will appear in front of the kart, and give them a minor speed boost. This can be dangerous as the leading racer could drop an item such as a Banana or a Bob-omb which the slipstreaming player would be unable to dodge.