2021 BMW M850i xDrive

The 2021 BMW M850i xDrive is a luxury grand tourer known for its blend of performance and comfort. It comes standard with a 4.4-liter twin-turbocharged V8 engine producing 523 horsepower and 553 lb-ft of torque. It is paired exclusively with an 8-speed automatic transmission. Owners generally praise the M850i for its powerful engine, luxurious interior, and comfortable ride, while some criticisms include its high price, large size making it less agile than smaller BMWs, and potentially complex electronics.

Engine

4.4L Twin-Turbocharged V8

• Oil Leaks
  • Description/Symptoms: Oil leaks can occur from various locations on the engine, including valve cover gaskets, oil filter housing gasket, and the rear main seal. Symptoms include visible oil drips under the car, a burning oil smell, and low oil levels.
  • Solution: Replacement of the leaking gasket or seal. Thorough cleaning of the affected area to ensure no residual oil is present.
  • Estimated Cost to Fix: $200 - $1,500+ depending on the leak’s location and complexity.
• Coolant Leaks
  • Description/Symptoms: Coolant leaks can occur from hoses, the water pump, or the radiator. Symptoms include a sweet smell, low coolant levels, and overheating.
  • Solution: Replacing the leaking component, pressure testing the system to ensure all leaks are addressed.
  • Estimated Cost to Fix: $150 - $1,000+ depending on the source.
• Turbocharger Issues
  • Description/Symptoms: Turbocharger issues can manifest as a loss of power, whistling or whining noises from the engine, and a check engine light.
  • Solution: Diagnosing the specific turbocharger issue (e.g., wastegate failure, bearing damage) and replacing or repairing the affected components.
  • Estimated Cost to Fix: $1,000 - $5,000+ depending on the extent of the damage and whether a rebuild or replacement is necessary.

Transmission

8-Speed Automatic (ZF 8HP)

• Rough Shifting/Hesitation
  • Description/Symptoms: Some owners have reported instances of rough shifting, particularly during downshifts or when accelerating from a stop. Hesitation can also occur when shifting between gears.
  • Solution: Software updates to the transmission control module (TCM) may resolve the issue in some cases. In more severe cases, valve body replacement or a transmission rebuild may be necessary.
  • Estimated Cost to Fix: $150 (software update) - $5,000+ (rebuild/replacement)
• Torque Converter Issues
  • Description/Symptoms: Torque converter shudder or slippage, especially at lower speeds. Can also cause vibrations.
  • Solution: Replacement of the torque converter. Flushing and refilling the transmission fluid.
  • Estimated Cost to Fix: $1,500 - $3,500+

Suspension

• Adaptive Suspension Malfunctions
  • Description/Symptoms: The M850i’s adaptive suspension system can experience malfunctions, leading to a warning light on the dashboard and a noticeable degradation in ride quality. One or more dampers may fail.
  • Solution: Diagnostic testing to identify the faulty component (e.g., damper, sensor, control module) and replacement of the affected part.
  • Estimated Cost to Fix: $500 - $2,000+ per damper, depending on the location and if OEM or aftermarket replacement parts are used.

Electrical

• Infotainment System Glitches
  • Description/Symptoms: Freezing, lagging, or unexpected reboots of the iDrive infotainment system. Connectivity issues with Bluetooth or Apple CarPlay/Android Auto.
  • Solution: Software updates can often resolve these issues. In more severe cases, replacement of the iDrive control unit may be required.
  • Estimated Cost to Fix: $0 (software update) - $1,500+ (control unit replacement)
• Sensor Failures
  • Description/Symptoms: Various sensors, such as parking sensors or sensors related to driver-assistance systems, can fail.
  • Solution: Replacing the faulty sensor.
  • Estimated Cost to Fix: $200 - $800+ depending on the sensor type and location.
• Battery Drain Issues
  • Description/Symptoms: Excessive battery drain, particularly when the vehicle is not in use, leading to starting problems.
  • Solution: Diagnostic testing to identify the source of the drain (e.g., faulty module, parasitic draw) and repair or replacement of the affected component. Registration of a new battery if the original battery failed.
  • Estimated Cost to Fix: $150 - $1,000+ depending on the cause.

Exterior

• Tail Light LED Failure
  • Description/Symptoms: Partial or complete failure of the LED elements in the tail lights.
  • Solution: Replacement of the entire tail light assembly.
  • Estimated Cost to Fix: $500 - $1,200+ per tail light assembly.

Interior

• Seat Adjustment Motor Failure
  • Description/Symptoms: Failure of the electric motors that control seat adjustment, leading to limited or no movement of the seat.
  • Solution: Replacement of the faulty motor or the entire seat adjustment mechanism.
  • Estimated Cost to Fix: $300 - $1,000+ per seat.
• Sunroof Issues
  • Description/Symptoms: Sunroof can be stuck open or closed. The sunroof can also make noises when opening or closing.
  • Solution: Repair or replacement of the sunroof motor. Sunroof track replacement.
  • Estimated Cost to Fix: $200 - $1,000+ depending on the part needed.

Summary

The 2021 BMW M850i xDrive, while lauded for its performance and luxury, can present owners with a range of issues. Engine oil and coolant leaks, along with turbocharger concerns, are common engine-related problems that can range in cost from a few hundred to several thousand dollars. The 8-speed automatic transmission can exhibit rough shifting, potentially necessitating expensive repairs. Electrical issues, such as infotainment glitches and sensor failures, are also relatively frequent. Suspension malfunctions and exterior lighting problems add to the list of potential concerns. While many of these issues can be addressed with software updates or relatively minor repairs, some may require significant investment, making thorough pre-purchase inspection and consideration of an extended warranty prudent steps for prospective buyers. The severity of these issues varies, but the potential for costly repairs should be a consideration when purchasing a used 2021 BMW M850i xDrive.