Used Mercedes-Benz GLS Brake Servo

Most GLS variants use an electrohydraulic or electromechanical brake booster rather than a traditional vacuum-based brake servo, particularly from the second generation (X167, 2019-onwards) which uses a fully electric brake boost system as part of its integrated braking setup. First-generation GLS models (X166, 2016-2019, badged as GL before 2016) did use a more conventional vacuum brake booster, so whether a traditional brake servo exists on your specific vehicle depends heavily on the generation and engine variant. If you are searching for a brake servo, confirm with the breaker exactly which braking system your registration corresponds to, as you may actually need an iBooster unit or brake actuator assembly on newer models.

No - the X166 (2016-2019) and X167 (2019-onwards) are entirely different generations with fundamentally different braking system architectures; the X166 used a conventional vacuum brake booster while the X167 moved to an integrated electric brake booster, so the parts are not interchangeable. You must source the correct unit for your specific generation, and you should confirm the exact part reference with the breaker against your registration number before purchasing.

Yes, engine size and output can influence the braking system specification on the GLS, as larger and more powerful variants may carry different brake system calibrations or booster sizing to match their greater weight and stopping demands. When contacting a breaker, always quote your engine size alongside your registration so they can match the correct unit, and do not assume a servo or booster from a smaller-engined GLS will be a direct swap onto a higher-output model.

Trim level alone does not affect brake servo or brake booster fitment on the GLS, as AMG Line and standard trim variants share the same running gear and braking system architecture within a given generation and engine combination. What matters is the generation (X166 or X167) and the engine fitted, not whether the car has AMG Line styling or interior upgrades - so do not let a trim name put you off a part that otherwise matches your generation and engine.

The 2018 GLS 350d sits within the X166 generation (2016-2019) and is likely to use a conventional vacuum brake booster rather than the fully electric system introduced on the X167. However, because mid-generation brake system changes are possible and specification can vary, you should confirm the exact braking system fitted to your registration with the breaker before ordering, rather than assuming based on year alone.

First confirm with the breaker whether your GLS uses a traditional vacuum brake servo (more common on X166 models) or an electric brake booster/iBooster (typical of X167), as these are completely different components and must not be confused. Give the breaker your full registration number, engine size, and build date so they can verify the correct unit, and ask them to cross-reference the part number from the donor vehicle against your own if possible before purchase.