The Egg Monster's appearance is based on a monster truck and Dr. Eggman's signature vehicle. The Egg Monster has a silver-colored body complimented by onyx and yellow stripes in a depression on the outside of the vehicle, with a red lining circling around the main body along the side. The exhaust pipes stick out of the vehicle with a white headlight and a black gauge in the front of the body and a "Egghead" or a Eggman symbol on the back. The undercarriage has a crimson finish revealing four individual chrome tubes with yellow shock absorbers connecting it to a cylinder with a red circular lining attach to the large tires with a various designs on the front. The front tires have a mango-colored circle with a silver lining around it and one bolt in the middle the back tires. There is a black ring and sectioned mango-colored things on the outside of the ring, and inside the ring, there is another mango circle with yet another bolt in the middle. The interior is black with a control board and two control sticks that Eggman uses to move the monstrous Egg monster, which is big enough for Eggman to fit snugly in it. (The control sticks reference the Dreamcast twin sticks accessory because of its appearance.)
In Sonic & All-Stars Racing Transformed, the Egg Monster looks almost completely different. It has a red paint job and what looks like his face, or a different version of his dream empire's insignia on the front. Other differences include its monster truck wheels being replaced by smaller black wheels, and it also has a different control scheme, with a conventional steering wheel instead of the twin sticks the original vehicle had. Transformations include the removal its wheels, revealing two hulls, making it a catamaran for a boat. As a plane, it could be passed off for the Eggmobile, as it removes its wheels and hovers. But to keep up with the competition in the air, Eggman crammed two giant rocket boosters into the machine to give himself an advantage in the air race.
In its battle state, the Egg Monster is complete with weaponry. One noticeable difference is that the vehicle is no longer a ground base vessel; it's airborne. Another change is that the exhaust pipes in the back turns into rocket booster, keeping the Egg Monster, or now can be called the Egg Mobile, hovering. More or less, the body of the car remains the same, except the shield protecting Dr. Eggman, which turns a rich shade of blue.
Muhauha! Now allow me to introduce you to my latest creation.
— Dr. Eggman performing the "missile madness" all-star move.
Dr. Eggman performs the All-Star Move "Missile Madness" by pressing a button on the Egg Monster. The wheels of the Egg Monster shrinking and retracting into the openings at the undercarriage of the Egg Monster and an array of projectile-firing weapons deploy from the top of the Egg Monster's body. These weapons also pop out on the right and left sides of the vehicle while constantly being propelled fiercely by thrusters on the backside of the vehicle. As Eggman controls the Egg Monster, he fires missiles, energy balls, and giant rockets. The explosions of the projectiles begin with fiery explosions forming into Eggman head symbols and leave behind clouds. After the move is over, its wheels pop out and it transforms back into its original state.
The All Star move Missile Madness's icon appears different compare to the Egg Monster's transformation, it suggests that the original Egg Mobile appears but Eggman's All Star move transformation looks different. It resembles a modified Egg Monster.