The BMW B58 is a 3.0-liter turbocharged inline-six that debuted in 2015 as part of BMW's modular engine family, quickly earning a reputation as one of the finest straight-sixes the company has ever built. Replacing the outgoing N55, the B58 pairs a single twin-scroll turbocharger with a closed-deck block to deliver strong, linear power and exceptional durability. Output ranges from 320 to 382 hp with 330 to 369 lb-ft of torque, spinning to a 7000 rpm redline.
Engineering & Specs
The B58 shares its modular architecture with BMW's smaller four-cylinder and three-cylinder units, using the same 500cc-per-cylinder philosophy found in the B48 four-cylinder and the B38 three-cylinder. Its key innovations set it apart from the older N55:
- Closed-deck block for improved rigidity and high-boost capability
- Single twin-scroll turbocharger integrated with the exhaust manifold
- Indirect charge-air cooling with a water-to-air intercooler
- Encapsulated design for faster warm-up and reduced emissions
The result is an engine that responds beautifully to tuning while remaining reliable in stock form. You can learn more about BMW's modular engine strategy in the BMW DNA encyclopedia.
Which BMWs Used It
The B58 powers a broad swath of BMW's lineup from 2015 to the present, including the 340i, 440i, 540i, M340i, M440i, X3 M40i, X4 M40i, and Z4 M40i. Notably, it also lives under the hood of the Toyota GR Supra, a testament to BMW's confidence in the platform. If you're unsure which engine sits in a specific car, the VIN decoder can confirm the exact powertrain.
Reliability & Buying Notes
The B58 is widely regarded as one of the most reliable modern BMW engines. The closed-deck block, robust internals, and refined cooling system address many of the weaknesses seen in earlier turbo sixes. Shoppers should still practice sound maintenance habits:
- Follow shorter oil-change intervals than BMW's factory recommendation
- Inspect for typical valve-cover and oil-filter-housing gasket seepage over time
- Keep cooling components fresh, especially on tuned or track-driven examples
Enthusiasts prize the B58 precisely because it tolerates aggressive tunes with excellent long-term durability, unlike the diesel-focused B57 that shares family DNA but serves a different purpose.
Legacy
The B58 has become a modern icon, blending old-school inline-six smoothness with new-school forced-induction muscle. Its combination of reliability, refinement, and tuning headroom has cemented its status as a benchmark straight-six for the 2010s and 2020s.