The Jet Mobile (ジェットモービル?) is a boss from Sonic & Knuckles, as well as its locked-on form, Sonic the Hedgehog 3 & Knuckles. It is fought in the second act of Mushroom Hill Zone after it is hit in a satellite like form in the ground. A glitch sometimes occurs during Knuckles' story, causing Robotnik to be the pilot of the machine instead of the EggRobo. When defeated, it is shown crashing into a large tree, with a hole at the bottom of the tree just large enough for Sonic, Tails, or Knuckles to run through.
Dr. Robotnik will not attack by himself; the way of him "attacking" are the spiked balls which Sonic, Tails, or Knuckles must jump over or dodge.
Defeating the Jet Mobile is by means of jumping and running. Sonic, Tails (lock-on only), or Knuckles must avoid the spike traps and the flames that it releases. If the player stops running their character will slowly scroll over to the left. As usual, this boss is harder for Knuckles.