2019 — 2026
3.0L Inline-6 Turbo (M256) - GLS 450
Petrol/Hybrid
During the test drive, pay close attention to the 9G-TRONIC transmission; if you notice any hesitation or clunky gear changes during stop-and-go city traffic, it's worth having a specialist technician verify if the transmission software is up to date.
Check the Airmatic suspension by toggling through the drive modes; listen for any persistent hissing sounds or check if the vehicle sits unevenly after being parked, as air strut components can be sensitive to New Zealand’s varied road surfaces.
Inspect the MBUX infotainment system thoroughly by testing voice commands and the steering wheel touch-pads; in some early X167 models, these interface components have occasionally required a software reset or hardware recalibration.
While driving at highway speeds, listen for wind noise around the panoramic sunroof seals; ensuring these are clean and well-lubricated is a common consideration for maintaining cabin quietness in these luxury SUVs.
Consider a full transmission fluid and filter service to ensure the 9G-TRONIC remains smooth.
Typically the interval where spark plugs and auxiliary drive belts should be assessed for wear.
A common point to have a specialist inspect the cooling system components and suspension air bellows for longevity.
Keep up with the strict engine oil change intervals using the specific Mercedes-Benz approved synthetic oil for the M256 inline-six.
Regularly clean the panoramic sunroof tracks and drains to prevent any debris buildup, especially given our wetter NZ climate.
Ensure the 48V mild-hybrid battery system is checked during your annual service to keep the EQ Boost functionality running efficiently.
Periodically verify the tyre pressures and tread wear, as the large wheels and heavy chassis can lead to faster wear on the inner edges.
Maintain a regular schedule of brake fluid flushes to keep the sophisticated electronic braking system performing at its best.
Estimated repair costs if issues arise
While these units are robust, air suspension components are wear-and-tear items. Depending on the car's history, you might eventually need to budget for a refresh of the air struts to maintain that signature Mercedes ride quality.
The GLS is a substantial vehicle, and the braking system works hard. If this component needs attention in the future, it is wise to account for the premium parts required for the larger brake rotors found on these models.
The M256 engine relies on a sophisticated 48V system. While usually very reliable, it is prudent to consider that, should the battery module require replacement outside of warranty, it is a specialized component that requires professional diagnostic time.
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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