Mercedes-Benz G550 4x4 high beam and low beam headlight bulbs both use D1S size. The replacement chart covers 2017 to 2018 vehicle production years with bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The D1S bulb type is specified for both the high beam and low beam headlight positions across all listed model years of the Mercedes-Benz G550 4x4, making it the sole bulb type present in these specifications.
The D1S is a discharge bulb belonging to the High-Intensity Discharge (HID) family, operating through an electrical arc between two tungsten electrodes within a quartz glass capsule filled with xenon gas and metal halide salts.
The "D" prefix in the D1S designation indicates a discharge-type bulb, while the "1" denotes the first generation of the standardized automotive HID series, and the "S" suffix specifies a projector-lens housing application rather than a reflector-based one.
D1S bulbs have an integrated igniter built directly into the bulb base, which distinguishes them from D2S bulbs that require a separate external igniter module.
For the 2017-2018 G550 4x4, the same D1S bulb serves both the high beam and low beam functions, a configuration made possible by the use of a bi-xenon projector system that uses a mechanical shutter to switch between beam patterns rather than separate bulb units.
D1S bulbs operate at a nominal power of 35 watts and produce a color temperature typically rated at 4200 Kelvin, which places their output in the white-to-slightly-blue range of visible light.
Because D1S bulbs contain mercury and operate under high internal pressure, they are subject to specific handling and disposal regulations in many jurisdictions.
The D1S specification is not interchangeable with D2S, D3S, or D4S bulbs despite their physical similarities, as differences in the igniter configuration and base design prevent cross-fitting without modification.