High-Speed Hijinks 2 is the fourth Challenge Act of City Escape 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 City Escape Act 2. The primary differences take the form of additional Horizontal Bars, rotating platforms, and many more enemies placed throughout.
Enemies move (and attack) twice as quickly as usual, making it slightly more difficult to get through without taking damage.
In this Challenge Act, the objective is to reach the Goal Ring at the end of the course.
The stage begins in the courtyard area after the boarding section. From there, it continues much like the normal Act until after running down the building. The player must then use Horizontal Bars and Rotating Platforms to progress, until they reach the Goal Ring at the end of the section.