Mercedes GLS X166 (2015 – 2019)

Reliability score : 7.4/10

The Mercedes-Benz GLS (X166 generation) is the extensive facelift of the GL. Renamed to emphasize its positioning as the "S-Class of SUVs", it is a luxurious 7-seater off-roader offering gigantic interior space and exceptional ride comfort thanks to its standard AIRMATIC air suspension. Although the cabin is starting to show its age compared to current standards (older generation COMAND infotainment system), it remains a formidable long-distance cruiser. The diesel engine (350 d) accounts for the overwhelming majority of sales in Europe, offering the best compromise between torque (620 Nm) and fuel consumption to move its 2.4 tons.

✅ Strengths

⚠️ Weaknesses

🎯 Verdict

The Mercedes GLS X166 is a formidable tool for hitting the road with the family in absolute comfort. The 350 d (OM642) version is by far the most rational and common choice. Although this diesel V6 is inherently robust, it requires meticulous maintenance and highway use to avoid clogging. Avoid examples that have been driven exclusively in the city. Anticipate a substantial maintenance budget, particularly for the running gear (tires, brakes) and the air suspension, which will inevitably require expenses. The V8 petrol versions (500/63 AMG) are to be avoided without a solid warranty due to the documented fragility of their cylinders.

Common issues

Dysfonctionnement du système AdBlue/SCR (capteurs NOx, pompe, chauffage) High
🔧 80 000 – 150 000 km
💶 800 – 2 000 €
Vérifier l'historique d'entretien du système AdBlue et les codes défauts.
Défaillance de la suspension pneumatique AIRMATIC (ressorts, compresseur, bloc de valves) High
🔧 100 000 – 180 000 km
💶 1 000 – 2 500 €
Tester le fonctionnement de la suspension, vérifier l'assiette du véhicule à l'arrêt.
Encrassement ou défaillance du filtre à particules diesel (DPF) Medium
🔧 120 000 – 200 000 km
💶 400 – 800 €
Privilégier les longs trajets réguliers pour une bonne régénération du DPF.
Fuites d'huile moteur (souvent au niveau du refroidisseur d'huile ou du turbo) / Actuateur de turbo Medium
🔧 150 000 – 220 000 km
💶 800 – 1 800 €
Inspecter le moteur pour toute trace de fuite d'huile, vérifier le bon fonctionnement du turbo.

Estimated maintenance costs

Oil change £110 – 190
Timing chain £1 200 – 2 500 (rarement nécessaire)
Complete brakes £500 – 1 000
Estimated annual budget £650 – 1 300

Indicative estimates (independent garage, UK market). Prices vary by region and year.