Here is the full list of all 12 Breakneck City achievements.
Defeat Wheeler
Defeat the Hunter
Defeat the Foreman
Defeat the Ninja
Defeat the Cyborg
Defeat Charles Dawn
Knock the Wheeler into the Trash
Knock the Hunter Through the Door
Knock the Foreman into the Water
Knock the Ninja Out The Window
Knock the Cyborg in the Pool
Knock Charles Dawn Over the Railing