This isn't a cameo for Sonic himself, but rather for Green Hill Zone.
This is a comic of "Mameshiba" which is a Japanese soy-bean based character. This bean is given a dog face & small dog ears. It was created for a TV commercial, where the bean would appear to people and tell them a random fact such as "a hippo has pink sweat".
When the commercials/character became popular, it got a comic book that is not just an ad for beans. In it, the bean creatures can use their ears to maniuplate things (as they have no limbs), and in this case it's a unicycle race. But, look at their race track: it's Green Hill complete with loop, tan ground, and even rings. Scan by RaeLogan
*It took longer to explain the premise than it did the cameo itself...because it is just that strange.