By working on my skills for half a year, I think I am now finally able to create a good running Animation! Ooh, looks like I've improved on my thumbnail and music choice too! (All this hype just to see a character moving its legs...)
This is the fastest he can go (~135 mph) although obviously I am bound to contradict this so like almost every single piece of animation in existence don't take this as if it's as definite as you can say you are breathing. Also this isn't really fast for a Sonic OC because I'm pretty sure that most major Sonic characters are probably able to run about 300 mph to even realise what Sonic is doing