Hello.. I am always driving around at night in GTA IV. Under you car there is a ugly 64x64 texture that's dark and pixelated. The textures were enhanced up to 1024x1024 for both bikes and cars!
Simply copy the lights_occluders.wtd to your [drive]:\Program Files\Rockstar Games\Grand Theft Auto IV\pc\textures
Be sure to create a backup if you wish to restore to the original textures.
Compatible with every version of the game from 188.8.131.52 - 184.108.40.206