2019 — 2026
3.0L I6 Turbo Petrol/Mild Hybrid (M256) - GLS450
Petrol
Test drive task: Perform a full-lock turn in a quiet parking lot. | Detail: Listen carefully for any clicking or binding sounds from the front end, as the complex suspension geometry in the X167 can sometimes show signs of wear in the control arm bushings.
Test drive task: Monitor the MBUX infotainment screen during a 20-minute drive. | Detail: Verify that the touchscreen remains responsive and doesn't flicker or reboot, as early software versions occasionally exhibit glitches that may require a dealer-led firmware update.
Test drive task: Switch the drive mode between Comfort and Sport several times. | Detail: Ensure the air suspension adjusts height promptly without dash warnings, as sensors can sometimes become sensitive to moisture ingress over time.
Test drive task: Check the 48V system integration during stop-start traffic. | Detail: Observe the transition of the mild-hybrid system; if the restart feels unusually jerky, it is worth asking for a diagnostic report on the battery state of charge.
Consider a major service including spark plugs and transmission fluid flush.
Inspect the air suspension bellows and level sensors for wear.
Review the coolant pump and auxiliary battery condition, as these components have a typical design lifespan approaching this mark.
Prioritize genuine Mercedes-Benz approved engine oils to keep the M256 engine internals happy.
Keep a close eye on your tyre pressure; the 21-inch or larger rims are sensitive to road hazards.
Ensure the cabin air filters are changed regularly to maintain the integrity of the complex climate control sensors.
Check for any signs of water ingress in the footwell area during a heavy rainfall, just to ensure drainage channels are clear.
Always use a reputable specialist or dealer for software updates to maintain seamless vehicle connectivity.
Estimated repair costs if issues arise
Given the weight of the GLS, the air struts are working hard. If they require replacement later, it involves swapping the unit and recalibrating the ride height.
This battery supports the electrical architecture. While durable, it is worth setting aside funds for a replacement as the vehicle ages to ensure the start-stop system continues to function smoothly.
The GLS450 is a large vehicle, and the braking system faces significant load. Budgeting for quality rotors and pads during your ownership cycle is a sensible move.
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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