Egg 1

Egg 1 is Yoshi's original kart in Mario Kart DS. It is essentially a Yoshi Egg on wheels.

A similar kart, called the Egg Rider, appears in Mario Kart Arcade GP 2 and Mario Kart Arcade GP DX as Yoshi's Kart.

Mario Kart DS
The Egg 1 has above average speed, high acceleration, and high handling, but also has low drift, weight, and items. Its name is clearly a pun on F-1 (Formula One). It is one of the lightest karts, and its weight is tied with the Poltergust 4000 and the Mushmellow.

Mario Kart 7
The Egg 1 reappears as a retro kart body in Mario Kart 7. It is one of the unlockable kart bodies in the game, and it offers an acceleration boost, at the expense of speed and weight. In fact, the Egg 1 is tied with the Birthday Girl and Bumble V for having the highest acceleration of all kart bodies.

In terms of its hidden stats, the Egg 1 offers one of the fastest sea speed stats (tied with the Tiny Tug) in the game, making it pretty effective for underwater racing.

The Mario Kart 7 incarnation of the Egg 1 also appears as a trophy in Super Smash Bros. for Nintendo 3DS, driven by Yoshi.

Mario Kart DS

 * Speed: 6/10
 * Acceleration: 9/10
 * Weight: 3/10
 * Handling: 9/10
 * Drift: 4/10
 * Items: 3/10

Mario Kart 7

 * Speed: -0.25
 * Sea Speed: +1.5
 * Air Speed: +0.5
 * Acceleration: +0.5
 * Weight: -0.25
 * Handling: 0
 * Sea Handling: 0
 * Air Handling: 0
 * Off-Road: 0
 * Mini-Turbo: +0.5
 * Stability: 0
 * Drift: +0.25