BMW 730d
Legendary common-rail straight-six diesel. Extremely smooth and long-lived; turbocharger and EGR valve are the most common weaknesses at high mileage.
Diesel Inline-Six
Beefy inline-six diesel — eats up motorway miles, but won't set the pulse racing.
Engine Weaknesses 6
As mileage increases the timing chain stretches and the chain tensioner loses its spring force. Broken plastic guide rails send fragments into the oil sump, which can damage the oil pump.
Symptoms: Rattling or clattering on cold start that improves once warm. Engine warning light.
The turbocharger wears through bearing problems or insufficient lubrication. Particularly at risk with infrequent oil changes or immediate shutdown after full-load driving.
Symptoms: Whistling noises, significant power loss, blue exhaust smoke, oil in the intercooler.
The plastic swirl flaps in the intake manifold break off and can be ingested by the engine. M57 engines built before 03/2004 are particularly at risk — complete removal is widely recommended.
Symptoms: Hesitation at low rpm; power loss; rattling from the intake area; in the worst case engine damage from ingested flaps; no fault code in early stages
Diesel injectors wear at high mileage. Diagnosis via cylinder balance test and return flow measurement. Individual injector replacement possible at around €450 including installation.
Symptoms: Rough running especially at idle (engine "runs like a tractor"), hesitation, increased fuel consumption, white/black smoke.
The M57 EGR valve becomes coked at high mileage. On the M57 cleaning can be done with the valve in situ — an advantage over newer engines. Regular cleaning every 60,000–80,000 km is recommended.
Symptoms: Sluggish throttle response; black smoke under acceleration; rough idle; power loss especially at low rpm
The M57 glow plugs must be replaced as a set. Defective glow plugs stress the DPF through incomplete combustion and can cause secondary damage to the glow plug control unit.
Symptoms: Poor cold-start performance; glow plug warning light on or flashing; increased fuel consumption in winter; fault entries for individual cylinder glow plugs
Vehicle Weaknesses 10
The electronic steering column lock can seize and prevent the car from starting. BMW charged around 1,800 € for repair. One of the most expensive electrical problems of this generation.
The E65 is considered an electrical nightmare: comfort access, ISOFIX, various control units, and body electronics can fail. Even minor repairs easily cost over 1,000 €.
The rear air suspension on the E65 is a frequent and expensive weak point. Air bellows and compressor typically fail from 100,000 km. The car sags at the rear, especially after standing.
Blocked panoramic roof drains let water through the C-pillar into the boot. Up to 7 control units are located there.
Hydraulic power steering pump fails. Faulty vane pump or leaking pressure hoses as causes.
A weak battery causes apparent multiple faults: Dynamic Drive, DSC, gearbox, and steering show simultaneous errors.
Plastic water pipe on top of the N62 V8 engine becomes porous and leaks. Coolant loss can lead to overheating.
Solenoid valves in the air suspension compressor scale up from condensation. Compressor can often be repaired cost-effectively.
The E65 comfort access fails frequently — from flat key batteries to faulty door handles and the CAS control unit. Diagnosis is complex and repairs accordingly expensive.
The E65's four-zone climate control frequently develops temperature regulation faults in individual zones. The water valve and IHKA climate control units are wear items that regularly fail after 10+ years.
Reports & Tests
15 owner complaints filed with NHTSA (2001–2008). Most reported: Electrical (3), Airbags (3), Suspension (3).