For the 2006 Volkswagen GTI, the low-beam headlight uses a D2S bulb. No high-beam bulb fitment is listed in the supplied data, so verify the original bulb before ordering. Fog-light fitment varies with the headlight setup: vehicles with halogen headlights may use H3 or H3C bulbs.
Front lighting also differs by configuration. With halogen headlights, the front turn signal and parking light use 3457A bulbs. With HID headlights, the front turn signal uses 64136, while the parking light may use 2825 or 98. The front side marker is listed as 2825 or 98.
Other notable exterior bulbs include 7506 for the reverse and rear turn signals, 7506R for the brake light, 5008 for the tail and rear side-marker lights, and 6418 for the license plate and vanity lights. The center stop light is LED. Interior locations may use 2825, 98, 6418, 6411, or 6428 depending on the location; compare courtesy-light options with the original bulb.