2019 — 2026
3.0L I6 Turbo (M256) - GLS 450 Mild Hybrid
Petrol
Cycle through all MBUX screens and infotainment menus while idling; if the system lags or flickers, it is worth noting as these units can occasionally experience software-related hiccups.
Listen for any subtle 'thrumming' or suspension noises while driving over uneven suburban tarmac, as the E-Active Body Control (if fitted) is sophisticated and warrants a smooth operation check.
Perform a cold start and listen for any momentary metallic rattle from the M256 engine; while mild hybrids are generally smooth, a clean idle is a good indicator of healthy timing components.
Check the operation of the second and third-row seat adjustments from the driver's console; these electric motors are reliable but deserve a quick confirmation that they move without hesitation.
Consider a transmission fluid flush and differential oil service to keep the 9G-TRONIC shifting smoothly.
A good point to inspect the auxiliary battery system and the 48V mild-hybrid hardware status.
Typically when suspension air-strut integrity and major cooling system hoses should be evaluated by a specialist.
Ensure the Service A and Service B intervals have been documented strictly via Mercedes-Benz or a qualified independent specialist.
Verify that the 48V battery system has been checked during the most recent scheduled dealer visit.
Check for any signs of water ingress in the footwells, just to be certain the sunroof drains are clear.
Confirm the air suspension raises and lowers promptly when the drive mode is switched to 'Offroad' or 'Sport'.
Keep an eye on tire wear patterns; the heavy kerb weight of the GLS makes wheel alignment crucial for tire longevity.
Estimated repair costs if issues arise
As these vehicles age, the rubber bellows on the air struts can eventually show signs of wear. It is wise to set aside some funds for potential future replacement to maintain that signature Mercedes ride quality.
While these units are robust, the 48V lithium-ion battery may eventually reach the end of its service life. Depending on the car's history, you might eventually need to budget for a specialized replacement.
Given the size and mass of the GLS, the brake pads and rotors are hardworking components. When the time comes to refresh these, budgeting for high-quality OEM replacements ensures optimal safety.
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Disclaimer: This report is generated with the assistance of AI analysis based on verified automotive data. While we strive for 100% accuracy, enthusiasts should always conduct physical inspections and consult service records. View Full Disclaimer