Audi Q8 I (4M8) (2018 – 2023)

Reliability score : 6.5/10

The first-generation Audi Q8 (code 4M8) is the large flagship coupe SUV of the brand with the four rings. Based on the MLB Evo platform (shared with the Audi Q7, Porsche Cayenne, VW Touareg, and Lamborghini Urus), it stands out with its muscular design, frameless doors, and ultra-technological triple-screen cabin. Designed to compete with the BMW X6 and Mercedes GLE Coupe, the Q8 offers an exceptional compromise between supreme comfort (especially with the air suspension) and dynamism, despite a weight easily exceeding 2.1 tonnes. In Europe, the range was largely dominated by V6 diesel engines (45 TDI and 50 TDI), perfectly suited to the vehicle's size, before the rise of plug-in hybrid versions (TFSI e). A facelift was carried out at the end of 2023. Overall design rating: Excellent, but

✅ Strengths

Imperial ride comfort (with adaptive air suspension)
Exceptional interior finish and top-flight soundproofing
Very generous rear roominess despite the coupe profile
V6 TDI engines (50 TDI) offering the best performance/consumption compromise
Stunning road handling thanks to rear-wheel steering (optional)

⚠️ Weaknesses

Disastrous reliability of the 48V alternator-starter (immobilizing breakdown)
Excessive weight (2.1 to 2.5 tonnes) leading to rapid wear of brakes and tires
All-touch ergonomics (lower screens) distracting while driving
Frequent electronic bugs (MMI, driving aids, cameras)
Prohibitive maintenance, insurance, and repair costs

🎯 Verdict

The Audi Q8 is a formidable flagship, particularly well-rounded in its V6 TDI versions (50 TDI) which combine quiet strength and astonishing fuel efficiency for its size. However, its reliability record is heavily burdened by the 48V alternator-starter (BSG) scandal that affects the V6 TDI and TFSI, causing sudden immobilizing breakdowns. Added to this are numerous recalls concerning the running gear and electronics. Buying a used Q8 requires absolute vigilance: demand a model whose 48V system has already been replaced with the new part number, check the wear of the rear tires, and plan for a substantial maintenance budget (brakes, tires, insurance). Favor a dealership purchase with an extended warranty (Audi Occasion :plus).

Common issues

Dysfonctionnement du système AdBlue (SCR) Medium

🔧 60 000 – 120 000 km

💶 800 – 1 800 €

Vérifier les alertes AdBlue, utiliser du liquide de qualité et éviter les bas niveaux.

Encrassement ou dysfonctionnement du FAP (Filtre à Particules Diesel) Medium

🔧 80 000 – 150 000 km

💶 1 500 – 3 000 € (remplacement)

Privilégier les longs trajets réguliers pour permettre la régénération du FAP.

Problèmes de suspension pneumatique (fuites, compresseur) High

🔧 90 000 – 180 000 km

💶 800 – 2 500 € par élément

Tester le fonctionnement de la suspension sur différentes hauteurs, écouter les bruits.

Glitches ou lenteurs du système MMI (Infotainment) Low

🔧 Variable

💶 100 – 500 € (mise à jour/réinitialisation)

S'assurer que le logiciel MMI est à jour lors de l'achat.

Estimated maintenance costs

Oil change	£160 – 280
Timing chain	£1,500 – 3,200 (rarely needed)
Complete brakes	£500 – 1,000
Estimated annual budget	£650 – 1,500

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