For the 2008 Audi A4, the listed low-beam and high-beam applications both use D1S bulbs. This fitment data does not specify a separate bulb by headlight design, so confirm the existing headlamp setup before ordering.
Front fog-light listings include both H11 LED and H16 LED. Because these are different applications, check the fog-light housing and the bulb currently installed to select the correct option.
Exterior lighting includes 7506 bulbs for the front and rear turn signals, reverse lights, and daytime running lights. The brake lights use 7506R bulbs, while the center stop light is listed as LED. The tail light uses 5007, and the license-plate and trunk lights use 6418.
For smaller lamps, parking, front side-marker, step, courtesy, glove-box, and interior applications are listed as 2825 or 98. Dome and engine lighting use 6411 or 6428, the map light uses 64111, and the vanity light uses 6418. Verify the original bulb where multiple options are shown.