2021 BMW M135i

The 2021 BMW M135i xDrive is a performance-oriented hatchback powered by a 2.0-liter turbocharged inline-4 engine producing 302 horsepower and 332 lb-ft of torque. It is only available with an 8-speed automatic transmission and all-wheel drive (xDrive). Owners often praise the car’s quick acceleration, sharp handling, and premium interior, while common criticisms include its firm ride, and polarizing styling.

Engine

2.0-Liter Turbocharged Inline-4 (B48)

• Coolant Leaks
  • Description/Symptoms: Coolant leaking from the thermostat housing or coolant hoses. May result in low coolant warning lights, overheating, and coolant smell.
  • Solution: Replace faulty thermostat housing or hoses.
  • Estimated Cost to Fix: $300 - $600+
  • Recalls: None Found
• Oil Leaks
  • Description/Symptoms: Oil leaking from valve cover gasket. Visible oil on the engine and potentially a burning oil smell.
  • Solution: Replace the valve cover gasket.
  • Estimated Cost to Fix: $200 - $400+
  • Recalls: None Found

Transmission

8-Speed Automatic (Aisin)

• Rough Shifting/Hesitation
  • Description/Symptoms: The Aisin transmission experiencing rough or delayed shifts, particularly when cold. Some owners also report hesitation upon acceleration.
  • Solution: Software update of the transmission control unit (TCU) may resolve the issue. If the problem persists, valve body replacement or a full transmission rebuild may be necessary.
  • Estimated Cost to Fix: $150 (Software Update) - $3000+ (Valve Body/Rebuild)
  • Recalls: None Found

Suspension

• Ride Comfort
  • Description/Symptoms: Harsh ride, especially on rough roads. Owners sometimes complain the suspension is too firm for daily driving.
  • Solution: No official fix. Some owners opt for aftermarket suspension components with softer spring rates.
  • Estimated Cost to Fix: N/A (Subjective preference)
  • Recalls: None Found

Electrical

• Infotainment System Freezing/Rebooting
  • Description/Symptoms: The iDrive infotainment system occasionally freezing, lagging, or rebooting unexpectedly.
  • Solution: Software update for the iDrive system. If the problem persists, the iDrive control unit may need to be replaced.
  • Estimated Cost to Fix: $0 (Software Update) - $800+ (Control Unit Replacement)
  • Recalls: None Found
• Sensor Malfunctions
  • Description/Symptoms: Random malfunctions of various sensors (e.g., parking sensors, tire pressure sensors). False warnings or non-functional systems.
  • Solution: Replace the faulty sensor.
  • Estimated Cost to Fix: $100 - $400+ (depending on the sensor)
  • Recalls: None Found

Exterior

• No Issues Found

Interior

• Rattling/Squeaking
  • Description/Symptoms: Rattling or squeaking noises coming from various trim pieces, particularly in the dashboard and door panels.
  • Solution: Secure or replace the loose trim pieces. Applying felt tape to contact points can sometimes mitigate the noise.
  • Estimated Cost to Fix: $50 - $300+ (depending on the severity and location)
  • Recalls: None Found

Summary

The 2021 BMW M135i xDrive, while offering a sporty driving experience, can be susceptible to certain issues. Engine oil and coolant leaks, transmission roughness, electrical glitches, and interior trim rattles are the most commonly reported problems. The severity of these issues can range from minor inconveniences to more costly repairs. Most of the issues are of moderate severity, and the costs to repair can be a concern, especially for out-of-warranty vehicles.