For the 2003 Audi S8, low-beam fitment depends on the headlight type: use an H1 bulb with halogen headlights or a D2S bulb with HID headlights. The supplied fitment data does not list a separate high-beam bulb, so confirm the high-beam application before ordering.
Fog-light fitment may be H3 or H3C. Other notable exterior applications include 2357A or 2827 for the front turn signals, 7506 for the rear turn signals and reverse lights, and 7528 for the brake lights. Tail-light and rear side-marker applications use 5007, while the center stop and parking lights may use 2825 or 98.
Interior and utility lighting includes 6418 for the license plate, step, trunk, vanity, and interior applications; dome lights may use 6411 or 6428. Check the existing bulb and housing when multiple options are listed.