From Sonic Retro
The Final GP is the secret Grand Prix in Sonic Drift 2. Once you get 1st place in all courses in Blue GP, you unlock this course. If you play as Sonic, Tails, Knuckles, or Amy, you race Eggman one-on-one in the Death Egg. If you play as Eggman, Fang, or Metal Sonic, you race Sonic one-on-one in the Death Egg.