The Mechanic Tails is a brand new skin that you can get in Sonic Speed Simulator. It will involve completing a specific task to get.
How to Unlock Mechanic Tails FAST & Secret Wrench Locations! (Sonic Speed Simulator)
If you've played Sonic Speed Simulator before, you already know that different skins aren't readily available. Instead, you have to unlock them by completing certain tasks. That said, a brand new skin called Mechanic Tails has been introduced to the game.
So if you want to unlock this skin, then this guide is for you.
To unlock the skin, you must first talk to Mechanic Tails. He will mention something about losing his tools and that he will need your help to find them. As such, your goal will be to find all 500 wrenches in exchange for his outfit.