High Speed Challenge 2 is the third Challenge Act of Speed Highway Act 1 in the console/PC version of Sonic Generations. It is unlocked after clearing every Stage in the Dreamcast era and is playable only as Classic Sonic.
This Act takes place within a slightly modified version of Speed Highway Act 1, with platforms and enemy placement moved around. Monitors containing Power Sneakers are here in a much larger quantity than usual.
The Act begins on the helipad later in the stage. The player will progress similarly to how they would in the normal version of the Act, continuing forward through platforming challenges, into a smaller building, then out across girders and platforms again toward the regular end of the Act. although they must now avoid enemies and scale large sections of vertical platforming while utilizing the Power Sneakers. Additionally, there are iron balls placed in the player's path that must be avoided in order to complete the Act quickly.