BMW M850i
Third-generation hot-V eight-cylinder — electric wastegates, 350 bar injection, forged internals. In Sport mode a rich V8 growl with turbo hiss; in Comfort barely audible. Throttle response noticeably more direct than TU/TU2 thanks to electric wastegates. The most reliable N63 variant, but the hot-V architecture remains: short oil change intervals (max. 8,000 km) with 0W-40 are mandatory, not an optional extra. Valve stem seals and timing chain guides remain as residual risk at high mileage.
530 hp V8 Coupe — Grand Tourer, Not a Track Toy
530 hp in the elegant 8 Series coupe — a pleasure on the motorway, V8 note in Sport rich and present. On tight corners the 2-tonne kerb weight and long wheelbase announce themselves. A grand tourer for distance, not for apexes.
Engine Weaknesses 5
The fundamental design with valve stem seals is retained. At very high mileages (>150,000 km) and aggressive use the seals can suffer thermal wear. Repair costs €3,300–3,800 (approx. 6–8 hours' work, engine removal required).
Symptoms: Increased oil consumption at very high mileages, slight blue smoke on cold start or after extended standstill, oil deposits in the exhaust
The plastic timing chain guide rails are sensitive to degraded engine oil. Extended oil change intervals (BMW Longlife) accelerate degradation. Complete engine removal (~40 labour hours) required; preventive replacement at >150,000 km is advisable.
Symptoms: Rattling on cold start, engine warning light, occasionally loud clattering with heavily degraded oil
The hot-V design also generates residual heat in the turbo oil feed lines after shutdown in the TU3. Immediate shutdown after full-load driving causes carbon deposits in the oil lines. Cases with fully coked lines at 60,000 km have been documented.
Symptoms: Power loss under load, occasional turbo whistling, in extreme cases blue smoke after a motorway run
350-bar direct injection without intake valve flushing — carbon deposits on intake valves are inevitable even in the TU3. Walnut blasting every 60,000–80,000 km is recommended; cost €400–900.
Symptoms: Power loss at part throttle, occasional rough idle, increased fuel consumption
The TU3 generation uses a separate cooling circuit for the turbochargers. Coolant loss documented at 14,000–15,000 km, often without visible leak. Turbo coolant hoses under the covers are a frequent leak point.
Symptoms: Coolant warning light without visible puddle, periodic coolant loss, coolant smell after shutdown
Vehicle Weaknesses 5
iDrive 7 system freezes, shows a black screen, or becomes unresponsive. Software restarts help temporarily.
Adaptive shock absorbers can be locked at maximum damping hardness through sensor faults or wiring corrosion.
The M Sport brakes squeal from day one, especially between 50 and 0 km/h. BMW rates this as normal. Pad cleaning and brake paste help only temporarily.
Repeatedly appearing coolant warning messages despite correct level. BMW confirmed evaporation and absorption into seals as the cause via a TSB.
Rear tyres wear on the inner edge from the high torque of the S63 V8TT already after 10,000–15,000 km.
Reports & Tests
5 owner complaints filed with NHTSA (2019–2026). Most reported: Cruise Control (2), Electrical (1), Engine (1).