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 14
The optional laser headlights cannot be repaired when faulty — they must be completely replaced. A single headlight costs around 5,700 € at BMW; total including fitting and calibration is 5,000–7,000 € per side.
The B58 in the 840i G14 tends to coolant loss through faulty heat exchangers and cracked plastic radiator fittings.
Like the G14, the G15's optional laser headlights cannot be repaired when faulty. A single headlight costs around 5,700 € plus ~1,000 € for fitting and programming.
Like the G15, the G16's optional laser headlights cannot be repaired when faulty. A single headlight costs ~5,700 € plus fitting and programming.
The G14's adaptive suspension shows damper wear at higher mileages. Standard dampers can be fitted as a cheaper alternative but require ISTA coding.
The adaptive suspension shows damper wear above 100,000 km. At over 1,800 kg, wear accelerates.
Faulty electronics in the comfort access door handle can cause a short circuit on the CAN bus line and elevated battery drain.
The iDrive 7 system shows sporadic navigation and Apple CarPlay crashes. GPS coordinates occasionally shown incorrectly. System was not updated to OS8.
M Sport or M Performance brakes tend to squeal heavily in city traffic and exhibit slight brake judder. Inherent to the pad material.
iDrive 7 shows sporadic system crashes, incorrect GPS data, and Apple CarPlay freezing. System was not updated to iDrive OS8 even after the facelift.
The deep front bumper on the G15 is particularly prone to stone chips. Paint thickness is described as below average for this price bracket. PPF is standard practice for many owners.
The G16's flat coupé roofline limits rear headroom. On older examples, creaking noises also emerge from the rear cabin.
The G16's iDrive 7 shows the same stability issues as the G15: sporadic CarPlay crashes, GPS errors, and occasional audio dropouts.
Same issue as the G15: M Sport brake pads are inherently prone to squealing at low speeds.