So, you guys know Sonic the Hedgehog, right? He's that little blue animal that runs really, really fast. Anyway, there has been a certain video about Sonic's top speed by a certain individual that makes theories about games: a Game Theorist, if you will. It was talking about how Sonic's true top speed is only around 80 m/s, and used Sonic Unleashed as the crux of that argument, stating that Unleashed is the fastest Sonic has ever been. Now, what if I told you that Sonic Unleashed was NOT the fastest Sonic has ever been?
Okay, how many of you remember the Sonic Advance games? They were pretty good GBA games, but we're not here to talk about their quality. I'm here to present Sonic's best speed feat performed throughout all of his games, and it just so happens that his best feat comes from Sonic Advance 2. Once you get all the Chaos Emeralds and beat the game with everyone, you'll access the true final boss of the game. It starts off with Vanilla, Cream's mother, being kidnapped by Dr. Eggman. Sonic finds out, proceeds to go Super, and chases Eggman down, where they fight in space.
Let's assume that the planet they were on (Mobius) has the same mass and density as Earth, and has a moon like Earth. With the positioning that Sonic and Eggman are in,as well as how Mobius is positioned, it would appear that they are fighting close to the moon. From the time it takes from Super Sonic to start moving to when he catches up with Eggman, it has taken around 7 seconds. At bare minimum, Sonic is around Massively Hypersonic + just for leaving Mobius' atmosphere in that time. For reference, the top speed of a human-made spacecraft is 201,168 m/s, and Sonic has gone faster than that. However, that's not the end of it. Remember that I had mentioned the moon, some time ago. Let's say that Sonic and Eggman are around the surface of the moon. The distance between the Earth and the moon is 238,900 miles, and Sonic had gotten there in roughly 7 seconds, like I had previously stated. This would put Sonic's top speed at 54,894,097.984 m/s. For reference, the speed of light is 299,792,458 m/s. This means that Sonic, at his top speed, is around 20% the speed of light. That's pretty fast, if I do say so myself.
TL;DR: Sonic's WAY faster than 80 m/s.