For the 2000 Audi A4, the supplied fitment data lists a D2S bulb for the low-beam headlight. No high-beam bulb is specified in the available data, so confirm the original bulb before ordering. No projector or non-projector headlight distinction is provided.
Front turn signals and front side markers may use 3457A, while another front turn-signal application is listed as 2827. Rear turn signals use 7506, and reverse lights use the same 7506 bulb. Brake and tail lights use 7528, with 2723 listed for the center stop light.
Other notable exterior bulbs include 64132 for parking lights, 6418 for the license plate, and 2825 or 98 for rear side-marker and step-light applications. Interior fitment also varies: dome and engine lighting use 6411 or 6428, while map lights use 64111. Courtesy-light options should be compared with the original bulb: 2825/98 are listed as one option, and 6418 as another.