The BMW 550i GT uses D1S bulbs for low beam headlights and D1S or H7 bulbs for high beam headlights, with bulb sizes varying by specific configuration. The replacement chart covers 2010 through 2015 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 D1S bulb type is the most prevalent specification across both high beam and low beam positions in the BMW 550i GT. It operates at 85V and 35W, using a high-intensity discharge (xenon) system rather than a heated filament. Its PK32d-2 base includes an integral ignitor, meaning the starting and control electronics are built directly into the bulb unit. This design is specific to projector-type housings.
The H7 bulb is a single-filament halogen type rated at 12V and 55W, fitted with a PX26d base. It carries ECE approval for use in Europe and worldwide markets, and also holds approval in the United States and Japan.
In the BMW 550i GT, the 2013 model year high beam position accommodates two distinct bulb types depending on headlamp system: D1S for vehicles equipped with HID headlamps, and H7 for those equipped with halogen capsule headlamps. This dual-fitment situation does not appear in any other model year within these specifications.
The low beam position across all model years from 2010-2015 is exclusively served by the D1S bulb. This applies regardless of whether the high beam position uses D1S or H7 in a given year.
For the high beam position, the 2010-2011 model years are specified with the H7 halogen bulb, while 2012-2015 model years (with HID headlamps) use the D1S. The two bulb types are not interchangeable, as they differ in operating voltage, wattage, base type, and the housing design they require.
The D1S and H7 bulbs follow ECE standards, which govern bulb geometry, photometric output, and base configuration. ECE-standard bulbs are subject to type-approval testing, meaning a given bulb code represents a fixed, regulated specification rather than a manufacturer-defined one.
Because the D1S incorporates an integral ignitor, it is not compatible with HID systems designed for bulbs that use a separate external ignitor. Substituting a bulb without an integral ignitor in a D1S-specified position would require a different ballast and ignitor arrangement.
The voltage difference between the two bulb types is substantial. The H7 operates on a standard 12V automotive circuit, while the D1S requires 85V during steady-state operation, with significantly higher ignition voltages at startup. The two systems rely on entirely separate electrical architectures within the vehicle.