BMW Série 8 G14/G15 (2018 – 2025)

Reliability score : 8.2/10

The BMW 8 Series (G15 Coupé, G14 Cabriolet, G16 Gran Coupé) marks the return of luxury grand touring for the Bavarian manufacturer, effectively replacing the 6 Series. Designed to compete with the Porsche Panamera, Mercedes S-Class Coupé, or Audi A7, it combines spectacular design with cutting-edge technologies. Although the market is massively shifting towards gasoline and hybrid, BMW has maintained a particularly relevant diesel offering (840d) for high-mileage European drivers. This version, powered by the robust B57 inline 6-cylinder engine, offers an exceptional compromise between GT performance (680 Nm torque) and fuel efficiency (often under 7 L/100 km on the highway). The model received a facelift (LCI) in 2022, primarily bringing technological updates (enlarged central screen) and

✅ Strengths

Exceptional B57 diesel engine (840d): a rare combination of performance (0-100 in 4.9s) and efficiency (range > 1,000 km).
Perfectly calibrated and indestructible ZF 8-speed automatic gearbox (Steptronic) if serviced.
Very high-quality interior finish and sound insulation.
Imperial road handling thanks to rear-wheel steering (Integral Active Steering) and xDrive transmission.
Very ergonomic and reliable iDrive 7.0 (then 8.0) infotainment system.

⚠️ Weaknesses

Steep depreciation, particularly on V8 and Diesel engines.
Symbolic rear passenger space on the Coupé (G15) and Cabriolet (G14).
Very high weight (often over 2 tons), which quickly wears out tires and brakes.
Prohibitive maintenance and insurance costs (very high-end vehicle).
Recurring recalls on the EGR system of diesel engines.

🎯 Verdict

The BMW 8 Series is a formidable touring machine. If your choice is the 840d, you are opting for one of the best diesel engines in the world (B57): torquey, quiet, and incredibly fuel-efficient. It is the rational choice par excellence for high-mileage drivers, provided that the EGR valve recall has been performed and that exclusively urban use, which would clog the DPF, is avoided. For more versatile use or if diesel puts you off, the 840i (B58) is the absolute best buy in terms of gasoline reliability. The V8 versions (M850i, M8) are reserved for enthusiasts willing to bear an exponential maintenance and fuel budget.

Common issues

Dysfonctionnements du système AdBlue (SCR) Medium

🔧 60 000 – 120 000 km

💶 800 – 2 000 €

Utiliser du carburant de qualité et éviter les trajets courts répétés.

Encrassement ou défaillance du filtre à particules (FAP) Medium

🔧 80 000 – 150 000 km

💶 1 200 – 3 000 €

Effectuer régulièrement des trajets longs pour permettre la régénération du FAP.

Problèmes logiciels ou bugs du système d'infodivertissement (iDrive) Low

🔧 Dès 20 000 km

💶 0 – 500 € (souvent mise à jour logicielle)

S'assurer que le logiciel est à jour lors des entretiens.

Estimated maintenance costs

Oil change	£140 – 230
Timing chain	£1 500 – 3 000 (si remplacement nécessaire, non routinier)
Complete brakes	£750 – 1 300
Estimated annual budget	£850 – 1 700

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