Mercedes Classe S W221 (2005 – 2013)

Reliability score : 7.4/10

The Mercedes-Benz S-Class (W221 generation) marks a strong comeback for the brand with the star in terms of build quality and reliability, following a highly criticized W220 generation. A flagship par excellence, it introduces cutting-edge technologies (night vision, Distronic Plus adaptive cruise control, dynamic massaging seats). The 2009 facelift brings LED daytime running lights, redesigned bumpers, and above all, a major update to the engines and the correction of early teething problems (notably on the petrol V6/V8s and the Airmatic suspension). Although generally very robust, the W221 remains a technological showcase whose maintenance requires a substantial budget.

✅ Strengths

Exceptional ride comfort (especially with Airmatic/ABC in good condition)
Very high level of soundproofing
Finish and material quality significantly improved compared to the W220
V6 CDI engine (OM642) very pleasant and durable if well maintained
Interior space and technological equipment still relevant today

⚠️ Weaknesses

Maintenance and spare parts costs worthy of a supercar
Disastrous reliability of the diesel V8 (OM629) and the Hybrid version
Balance shaft sprocket problem on pre-2008 petrol V6/V8s
ABC (Active Body Control) suspension ruinous to maintain
Imposing size and rapid wear of tires/brakes

🎯 Verdict

The Mercedes S-Class W221 is an excellent luxury sedan, much better born than its predecessor. For a diesel purchase, the 3.0 V6 CDI (OM642) is the only reasonable choice, provided you check that the oil cooler seal has been replaced and the gearbox oil has been changed. Absolutely avoid the diesel V8 (S 420/450 CDI) and the 4-cylinder (S 250 CDI) which is too fragile. Favor a facelifted model (post-2009) which corrects the early teething problems of the electronics and engines. Plan a financial reserve of €2,000 to €3,000 to cover any potential whims of the air suspension or sensors.

Common issues

Défaillance de la suspension pneumatique Airmatic (amortisseurs, compresseur ou bloc de vannes) High

🔧 100 000 – 200 000 km

💶 800 – 2 500 € par élément (amortisseur, compresseur, bloc de vannes)

Vérifier la hauteur du véhicule après stationnement prolongé et l'absence de bruits anormaux.

Problèmes de la boîte de vitesses automatique 7G-Tronic (platine électronique ou bloc hydraulique) High

🔧 120 000 – 200 000 km

💶 1 000 – 2 500 € (platine), 2 000 – 4 000 € (bloc hydraulique)

Exiger l'historique des vidanges de boîte. Tester les passages de rapports à chaud.

Colmatage du Filtre à Particules (FAP) ou dysfonctionnement de la vanne EGR Medium

🔧 100 000 – 180 000 km

💶 800 – 2 000 € (FAP), 300 – 800 € (EGR)

Privilégier les longs trajets. Vérifier les voyants moteur et l'historique d'entretien.

Défaillance des injecteurs de carburant diesel Medium

🔧 150 000 – 250 000 km

💶 300 – 700 € par injecteur (souvent plusieurs à remplacer)

Écouter le moteur au ralenti pour des claquements. Vérifier la présence de fumée excessive.

Estimated maintenance costs

Oil change	£100 – 180
Timing chain	£1 300 – 2 800 (si remplacement nécessaire)
Complete brakes	£400 – 750
Estimated annual budget	£750 – 1 500

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