For the 2015 Subaru Legacy, the low-beam bulb depends on the headlight system: models with halogen headlights use an H11, while models with HID headlights use a D4S. The high-beam bulb is 9005.
Fog-light fitment is listed as either H11 LED or H16 LED. The 9005 bulb is also used for the daytime running lights. Front and rear turn signals use amber 7440A bulbs, while the reverse lights use 921 bulbs.
Several exterior lamps are LED-equipped, including the brake lights, center stop light, parking lights, and tail lights. Front and rear side markers use 168NA bulbs. License-plate lighting may use 168 or 917 bulbs. Interior fitment includes DE3175 for the dome and map lights, with 168 or 917 listed for other interior lighting. Trunk-light options are 194 and 7441.