Audi A6 C8 (4K) (2018 – 2025)

Reliability score : 7.4/10

The eighth-generation Audi A6 (internal code C8 or 4K) was launched in 2018. Based on the MLB Evo platform, it marks a major technological turning point with the widespread adoption of mild-hybridization (12V MHEV on 4-cylinders, 48V on V6s) and the introduction of the dual 'MMI Touch Response' touchscreen in place of the physical rotary controller. Positioned as a premium executive car (E-segment), it excels with its sound insulation, meticulous finish quality, and highway comfort. A minor facelift occurred in mid-2023, bringing subtle aesthetic changes (revised Singleframe grille) and an infotainment update. Although demand for diesel has decreased, TDI engines remain the core of the range in Europe for high-mileage drivers, offering remarkable range and torque, despite some reliability

✅ Strengths

Benchmark finish and assembly quality in the category
Exceptional sound insulation (especially with acoustic glazing)
Efficiency and range of TDI engines (over 1,000 km with the V6)
High-performance onboard technology and Matrix LED / HD Matrix lighting
Imperial road handling with Quattro transmission and rear-wheel steering (option)

⚠️ Weaknesses

Disastrous reliability of the 48V starter-generator on V6 engines (TDI and TFSI)
Annoying response time (lag) of the Tiptronic 8 gearbox on V6 TDIs, especially when restarting or needing quick overtaking
Distracting all-touch ergonomics (MMI Touch Response) while driving
Reduced boot volume on plug-in hybrid versions (TFSI e)
Cost of spare parts and labor in the Audi network

🎯 Verdict

The Audi A6 C8 is a masterful executive car that borders on perfection in terms of comfort and finish. However, the choice of engine is crucial for peace of mind. If you are looking for a diesel, the 40 TDI (4-cylinder) is the sensible choice: very economical, sufficiently powerful, and generally reliable. The V6 TDI (45, 50, S6) offer superior driving pleasure but are plagued by the recurrent and costly 48V starter-generator problem, as well as a Tiptronic gearbox that is sometimes sluggish. If you buy a V6 (TDI or TFSI), demand an extended warranty or proof that the 48V system has been made reliable with the latest revised parts. The 4-cylinder petrol versions (40/45 TFSI) are excellent, very reliable alternatives for those who drive less than 20,000 km per year.

Common issues

Dysfonctionnements du système AdBlue (capteurs, pompe, cristallisation) Medium

🔧 60 000 – 150 000 km

💶 800 – 1 500 €

Vérifier l'historique des rappels et l'utilisation (longs trajets).

Défaillance de composants du système Mild-Hybrid (MHEV) 48V (alterno-démarreur, batterie) High

🔧 50 000 – 120 000 km

💶 1 800 – 3 500 €

S'assurer du bon fonctionnement du système MHEV et de la batterie 48V.

Glitches et lenteurs du système d'infodivertissement MMI Touch Response Low

🔧 Dès 20 000 km

💶 100 – 2 000 €

Tester toutes les fonctions MMI avant achat.

Encrassement ou défaillance de la vanne EGR Medium

🔧 80 000 – 180 000 km

💶 700 – 1 300 €

Privilégier les véhicules ayant fait de longs trajets réguliers.

Estimated maintenance costs

Oil change	£100 – 180
Timing chain	£1,800 – 3,500 (si remplacement nécessaire)
Complete brakes	£500 – 850
Estimated annual budget	£700 – 1,400

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