When using Acceleration, Sonic's acceleration rate will be greatly increased, allowing him to reach top speed faster. While useful for long runs, it also makes it more difficult for the player to control Sonic precisely.
To unlock Acceleration, the player must collect all five Red Star Rings from Green Hil Act 2. It will then automatically become available in the player's Skill inventory. It can only be equipped to Modern Sonic and costs 10 Skill Points to be equipped.