Super-Speed Stage

Super-Speed Stages (commonly known by fans as Mach Speed Sections) are a game mechanic in Sonic the Hedgehog (2006), which is the game's unique variant of Auto Running. In this mode, he is assumed to be traveling at his top speed. An early variant is found in Sonic Adventure. These stages appear in the following levels: Wave Ocean, Crisis City, Radical Train, Kingdom Valley.

Description
At the end of certain levels, Sonic will suddenly speed up to nearly absurd speeds, perhaps even his true speed. In this mode, the player only controls Sonic by moving left or right, and jumping. No attacks are to be used. These sections were one of the few things that were carried on to Sonic Unleashed. What made these sections difficult was that if Sonic were to touch anything while running, he loses rings or dies.

Manual
''There's no stopping Sonic during these Super-Speed Stages. Guide him left and right through the fast-paced course, jumping over obstacles in his way to reach the goal in as short time as possible, and in one piece. Note that attack moves are not used during these stages.''

Trivia

 * In these sections, Sonic can not access any Gem Powers.
 * The player cannot destroy any enemies in these sections, as they only damage Sonic.
 * If the player has purchased the Blue Gem, he/she can achieve Mach Speed, and can use it at will (besides the actual sections), though it only lasts a short time.
 * In the Tokyo game show trailer, when Sonic wall-jumps in these sections, he would jump, do a spinning motion, then land on his feet. However, in the final release, Sonic would jump and look like he is going to land on his head, but is on his feet a split second later. The animation is probably missing due to the game being rushed.
 * There seems to be a similar section found in Sonic Adventure, when Sonic is running down the side of a building in the Speed Highway stage, though there are no enemies to be found. Also, when Sonic makes physical contact with something, he merely stumbles for a few seconds, intead of losing rings.
 * In Sonic Generations, at the end of Crisis City is a section meant to represent the Super-Speed Section from the original, tough in the levels redesign. There is also no Auto-run, so the player must control Sonic manually.