2019 — 2026
3.0L Inline-6 Turbo Diesel (OM656) - GLS 400d
Diesel
Check the air suspension ride quality | Observation: While driving, ensure the vehicle levels correctly and doesn't lean or 'slump' overnight. It is common in luxury SUVs of this size for the air bellows to wear over time.
Monitor the MBUX infotainment screen | Observation: Test this by cycling through the dual-screen interface repeatedly during your drive; occasional software glitches or screen flickering can indicate underlying electronic connectivity issues.
Listen for transmission shift quality | Observation: While driving at low speeds, observe if the 9G-TRONIC gearbox feels jerky; while usually smooth, some examples may require a transmission fluid flush to maintain crisp shifting.
Verify the operation of the panoramic sunroof | Observation: Check this by opening and closing the roof; if it stutters or struggles, the tracks may need cleaning or recalibration, which is quite common for these large glass panels.
Recommended major service, typically involving transmission oil change and cabin filter refresh.
Often the time to inspect auxiliary drive belts and ensure the diesel particulate filter (DPF) regeneration cycles are operating optimally.
Consider a comprehensive cooling system health check and inspection of suspension bushings.
Strictly adhere to the 15,000km or 12-month service intervals using Mercedes-Benz approved synthetic oil.
Keep a close eye on the AdBlue levels, as the OM656 engine relies on consistent quality fluid for emission compliance.
Ensure all software updates are applied by an authorized dealer or specialist to keep the complex MBUX system running smoothly.
Regularly clean the drain paths around the sunroof and exterior vents to prevent debris buildup and potential water ingress.
Have the brake discs and pads measured at every service, as the weight of the GLS can lead to faster wear on consumables.
Estimated repair costs if issues arise
Future Budget Planning: These provide the signature smooth ride, but as they age, you might eventually need to budget for a replacement to maintain that comfort.
Future Budget Planning: To keep the 9G-TRONIC shifting like a dream, it is common to consider a full fluid and filter service periodically.
Future Budget Planning: Modern diesel engines have sophisticated emission systems; if warning lights appear in the future, it may require professional diagnostic and cleaning.
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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