Overdrift is the first Challenge Act of Speed Highway Act 2 in the console/PC version of Sonic Generations. It is unlocked after clearing every Stage in the Dreamcast era and is playable only as Modern Sonic.
This Act takes place within a slightly modified version of Speed Highway Act 2, full of sharp twists and turns.
The player begins in the lobby of the skyscraper before running down a long, twisting highway, being sent in the opposite direction, and ending at the toll booth. In order to maintain high speeds, the player must make use of the Drift to avoid constantly running into walls. After running down the pathway, Sonic will be sent flying in the opposite direction, where he must continue drifting around corners until he reaches the Goal Ring.