>>718959909
>muh hub world!
and the multiple character storylines
and the return of character upgrades in said hubs
and sonic's moveset basically being a return to his SA2 gameplay after the changes made for heroes
and knuckles/rouge having segments where they hunt for things
and the shooting mechanics being folded into shadow and omega's gameplay
and the blatant callback to emerald coast, orca chase included
and eggman flying around in a second (third, technically) egg carrier
and iblis essentially just being a lava-themed perfect chaos
and the chao in space 3 poster

when you boil it down, 06 might be a closer sequel to SA1 than SA2 was
it's clear the devs were intending the game to be a follow-up to SA1/2, marketing just stepped in at some point and wanted the project to be called something else, probably following naming trends of pretty much every other IP at the time

>>715113485
His friends are participating in a vehicle-based competition, and he likes hanging out with his friends, hence the usage of a vehicle. That's it.
Also certain parts of the race in recent games require traveling across air and water, which Sonic would obviously need help with to some degree.

Might as well ask why Sonic owns a plane.