The 2025 BMW X3 M50 introduces a new chapter in BMW’s performance SUV lineup, not only replacing the brilliant X3 M40i, but also featuring an updated B58 engine. Codename B58B30M2, the updated 3.0 liter six-cylinder turbocharged comes with a series of hardware and software upgrades, building upon the already successful previous generations.

Engine Specifications

The workhorse B58 engine came to life in 2015. It’ part o f BMW’s modular engine family, each engine using a displacement of 500 cc (30.5 cu in) per cylinder. It’s the only 3.0 liter six-cylinder turbo powerplant offered today by BMW and it has the following specifications:

  • Bore x Stroke: 82.0 mm x 94.6 mm
  • Displacement: 2,998 cm³
  • Compression Ratio: 11.0:1
  • Max system power: 393 @ 5,200-6,250 rpm
  • Max system torque: 428 lb-ft @ 1,900-4,800 rpm
  • Output per liter: 131.0 hp/liter

Engine Updates

There are several innovations that the B58B30M2 variant brought to the BMW lineup in 2022, and according to BMW, additional updates were also implemented in the variant in the new 2025 BMW X3 M50 The B58B30M2 engine operates on the Miller cycle and incorporates several upgrades, including:

  • Injection System and Crankshaft: Enhanced for improved performance and durability.
  • Ignition System and Exhaust Gas Routing: Revised for optimized efficiency.
  • eVANOS: Electrically controlled camshaft adjustment for precise engine management.
  • Turbocharger: Adjusted for better power delivery.
  • Oil Supply: Further optimized to ensure efficient lubrication under high-performance conditions.

Additional M-specific enhancements include a robust crankshaft drive, optimized piston oil supply with cooling channels, and new main bearing shells and caps. The M TwinPower Turbo technology features increased turbo performance and dual injection for improved mixture preparation.

Mild-Hybrid Powertrain

We’ve talked at length about the benefits of a mild-hybrid powertrain. So it comes as no surprise that the new X3 M50 also gets the 48V mild-hybrid tech. For 2025, the BMW X3 M50 combines the B58 engine with a mild-hybrid system, integrating a crankshaft-mounted starter generator. Thanks to that, the hybrid system delivers a total output of 393 hp and 428 lb-ft (580 Nm) of torque. The combustion engine alone produces 375 hp and 398 lb-ft (540 Nm), while the electric motor contributes 17 hp and 147 lb-ft (200 Nm).

Performance Metrics

  • 0 to 62 mph (100 km/h): 4.6 seconds
  • 0 to 60 mph (96 km/h): 4.4 seconds (US-spec model)
  • Top Speed: Electronically governed at 155 mph (250 km/h)

The electric motor is integrated into the eight-speed automatic transmission, contributing to smooth and rapid gear changes. As we’ve tested back in April on the track, this setup supports the X3 M50’s acceleration and drivability across various conditions. It’s certainly more responsive, especially in this M50 application where the X3 is larger and heavier than ever before.

BMW is expected to continue enhancing the B58 engine, particularly as several of their new models are planned to have production cycles extending well beyond 2035.