The Egg 1 is a kart for Yoshi in Mario Kart DS. It is in the shape of an Yoshi Egg. This kart, the Standard YS, and the Cucumber are Yoshi's karts in this game. This kart is very popular in Time Trial, having great speed, great Acceleration, great Handling, perfect drift, and being light. This is a great kart for snaking, the others are the Dry Bomber and the ROB-BLS.
In Mario Kart Wii, since each racer has a kart that is evenly distributed and may be shared with other racers, and snaking removed, Yoshi has become not as stellar as before. (This is also true for Toad and Princess Peach.)
It also appears in Mario Kart 7 as an unlockable Retro Kart body.