The BMW B58 is a 3.0-liter turbocharged inline-six introduced in 2015 as the successor to the N55. It powers the BMW M340i, M440i, 540i, X3 M40i, Z4 M40i, and the Toyota GR Supra A90 — a collaboration that doubled the B58 tuning community overnight.

The B58 addressed every major weakness of the N54 and N55. Closed-deck block — stronger than the open-deck N55. Integrated water-to-air intercooler. 350-bar fuel injection. Forged crankshaft and connecting rods — stock internals hold 500+whp on well-maintained builds.

The B58 earns an 8.6/10 reliability score among enthusiasts — on par with legendary engines like the Toyota 2JZ when properly maintained. No wastegate rattle. No HPFP epidemic. No injector failures at 20,000 miles. This is what BMW learned from a decade of N54 and N55 ownership feedback.

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