5. Rally Mode
The "Backseat Driver" achievement certainly distinguishes itself as one of the strangest and most unexpected of the lot, unlocked by playing GTA Online and " a driver to 1st place as co-driver in Rally Mode". Wait, Rally Mode? Indeed, it appears that there's some sort of rally-based mini-game in GTA V's online component, requiring two players to get in a car together, with one directing another of the route. Quite how this will work is anyone's guess, but I suspect it will involve one player having a map of the route, and needing to direct his buddy by means of voiceover comms. It sounds potentially awkward, though Rockstar are known for thinking things through rationally, and it certainly sounds intriguing if nothing else.