Mercedes-Benz GL550 high and low beam headlights utilize D1S and H7 bulb sizes depending on configuration. The replacement chart covers 2008 to 2016 model years with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The H7 bulb is a single-filament halogen type rated at 12V and 55W, using a PX26d base. It operates under ECE standards and holds approval for use in the United States and Japan as well as European and worldwide markets.
The D1S bulb is a high-intensity discharge xenon type rated at 85V and 35W, using a PK32d-2 base with an integral ignitor built into the bulb body. It is designed specifically for projector-type housings and is governed by ECE standards for European and worldwide use.
The integral ignitor on the D1S bulb is a notable fitment consideration. Because the ignitor is part of the bulb itself rather than a separate ballast-mounted component, the D1S is not interchangeable with discharge bulb types that use an external ignitor, such as the D2S.
On the Mercedes-Benz GL550, the 2013-2016 model years list both D1S and H7 as valid high beam bulb sizes, with fitment determined by whether the vehicle was equipped with HID or halogen capsule headlamps at the time of manufacture.
For the low beam headlight position, the dual-fitment pattern of D1S and H7 extends across the full 2008-2016 range, meaning headlamp system type is the determining factor for the correct bulb in all listed years.
The high beam position for the 2008-2012 model years lists only H7 without a halogen capsule qualifier, while the low beam position for those same years lists H7 specifically under the halogen capsule condition. This distinction reflects a difference in how the high beam circuit was configured relative to the low beam on vehicles without HID systems.
The H7 and D1S bulbs share no base compatibility. The PX26d base of the H7 and the PK32d-2 base of the D1S are physically distinct, making cross-substitution between the two types impossible without modification to the housing socket.
The voltage difference between the two bulb types is substantial. The H7 operates at 12V, consistent with a standard automotive electrical system, while the D1S requires 85V, supplied by a dedicated HID ballast. This reinforces that the two systems are entirely separate and non-interchangeable at the vehicle wiring level.