When using Auto-Gauge, the Boost Gauge will automatically replenish itself with small amounts of energy over time if it is not full.
To unlock Auto-Gauge, the player must collect all five Red Star Rings from Speed Highway Act 2. It will then automatically become available in the player's Skill inventory. It can only be equipped to Modern Sonic and costs 30 Skill Points to be equipped.
- The Auto-Gauge Skill has the same icon as the Endless Boost Skill.