For the 2018 Audi S3, both the low-beam and high-beam headlights use integrated LED lighting. The supplied fitment data does not list a replaceable halogen or HID bulb number for either beam, so confirm the complete headlamp assembly and vehicle equipment before ordering a replacement.
Other exterior lighting is also listed as LED, including the front and rear turn signals, daytime running lights, cornering lights, parking lights, side markers, tail lights, brake lights, center stop light, reverse light, and license plate light. No separate fog-light bulb fitment is provided.
For the interior, the dome, glove-box, map, trunk, and general interior lights are listed with bulb numbers 2825 and 98. The vanity light uses bulb number 6418. Check the individual lamp socket when replacing interior bulbs, since the data lists both 2825 and 98 for several locations.