
(Click for general game info.)
System requirements:

Latest drivers: (as at 21/12/2017)
Nvidia: 388.71
AMD: 17.12.2
Intel: Depends on your processor; download the driver update utility
Benchmarks:
Computer Base (German; launch build)
GameGPU (Russian; launch build)
Guru3D (English; launch build)
PC Games Hardware (German; launch build)
TechPowerUp (English; launch build)
Tips and tricks:
Benchmarks (NV), settings comparisons, and recommended settings (NV): See Nvidia's tweak guide. (Credit to AndyBNV.)
Cap the framerate/potentially improve frametimes: Download RivaTuner Statistics Server, input your desired framerate limit in the "Framerate limit" box, and hit enter (the program comes bundled with MSI Afterburner and earlier versions of EVGA PrecisionX). Alternatively, those with an Nvidia GPU have the option of Nvidia Inspector, which can also be used to impose a framerate cap, either in a similar manner to RTSS or by way of forcing a different vsync interval (click the small tool icon to open the game profile section).
Note: Useful if you your system can't maintain, say, 60fps and you're sensitive to the wild fluctuations, or you're experiencing uneven frametimes. The greater window the engine has to render a given frame, if you're imposing a lower framerate than the game can otherwise provide, may also help in alleviating stuttering related to data streaming.
Stop the game from crashing after 15 minutes on touch-capable systems running Windows 10: Open the task manager, switch to the Services tab and disable TabletInputService.
Enable support for bluetooth adapters, DLL injectors/external hooks and possibly other stuff that ought to work: Disable the game's anti-cheat system by launching it with the command -eac_launcher. (Credit to PHOENIXZERO.) To do so if launching the game through Uplay, right-click it -> click "View game details -> select "Properties" from the menu -> click "Add launch arguments" -> input -eac_launcher into the field; if you have the Steam version, right-click it -> click "Properties" -> click "Set launch options" -> input -eac_launcher into the field. Alternatively, if you're running either version via a desktop shortcut, you can achieve the same result by righting-click it -> clicking "Properties" and adding -eac_launcher to end of the target field, separating the two with a space.
Note: Disabling EAC will also completely disable the the multiplayer component.
Fix aspect ratio issues on 4K/UHD TVs: Follow the instructions here. (Cried to Paz @ Steam Community via jackft.)

Graphics settings:
Video adapter: Self-explanatory
Window mode: Windowed; Borderless window; Fullscreen borderless; Multimonitor borderless; Fullscreen
Display: Self-explanatory
Resolution: Self-explanatory
Monitor refresh rate: Self-explanatory
V-sync: Off; Normal; Sparse
FPS limit: Off; 30 -> 125 in increments of 5
Field of view: 70° -> 110° in increments of 2°
Pixel density: 0.5 -> 1.5 in increments of .05
Menu position: Self-explanatory
Multimonitor HUD: Auto; Fixed aspect; Fit to display
Graphics quality: Low; Medium; High; Very High; Ultra; Custom
Geometry: Low; Medium; High; Very High; Ultra
Extra details: 0% -> 100% in increments of 5%
Terrain: Low; High; Ultra
Vegetation: Low; High; Ultra
Texture resolution: Low; Medium; High; Ultra (requires the optional UHD texture pack)
Texture filtering: Low; High; Very High; Ultra
Shadows: Low; Medium; High; Very High; Ultra; PCSS; HFTS
Headlight shadows: Off; Your car; 2 cars; 3 cars; 4 cars
Water: Low/High
Reflections: Low/High
Screenspace reflections: Off; Medium; High; Very High; Ultra
Dynamic particles: Off/On
San Francisco fog: Off/On
Depth of field: Off/On
Motion blur: Off/On
Bloom: Off/On
Ambient occlusion: Off; SSBC; HMSSAO; HBAO+
Temporal filtering: Off/On
Multisample anti-aliasing: Off; MSAA x2; MSAA x4; MSAA x8; TXAA x2; TXAA x4; TXAA x8
Post-process anti-aliasing: Off; FXAA; SMAA; SMAA T2x