A decade into production, BMW’s B58 turbocharged inline-six has done something few modern engines manage: it has only grown more impressive with age. What began as a replacement for the well-regarded N55 has evolved into one of the most versatile powerplants in the automotive world — turning up in everything from compact sports coupes to hardcore off-roaders, and even in a Toyota sports car that carries one of the most storied nameplates in enthusiast history. The B58’s staying power isn’t just a matter of longevity; it’s a testament to how well the engine was engineered from the start.
While it’s often tricky to ascertain the reliability of engines in modern vehicles, the sheer range and breadth of ability the B58 brings to the table is enough to arguably justify it as BMW’s most reliable modern engine, used from entry-level Bimmers to the most luxurious models, Toyota sports cars, and even hardcore off-roaders.
At its core, the B58 is based on a modular architecture (that also includes the B38 1.5-liter inline-three and B48 2.0-liter four-cylinder), boasting six cylinders, a single turbo, and a variety of outputs across five core versions (excluding the S58, the performance version from BMW’s M division). With the basics in mind, let’s look at the wide variety of applications where the B58 works its magic, proving itself a modern legend in the realm of six-cylinder engines.
BMW Z4 M40i
BMW Z4 M40i
Engine Version
B58B30O1
Power
382 hp
Torque
369 lb-ft
Drivetrain
Front engine, RWD
Transmission
6-speed manual, 8-speed automatic
The third-generation BMW Z4 Roadster is arguably more famous for being the mechanical sibling to the A90 Toyota Supra than for its own merits, but it’s a stellar drop-top sports car in its own right. Despite sharing the B48/B58 engine range, the same transmission options, and the same outputs as the Supra, the Z4 carves out its own identity. BMW’s B58B30O1 version of the engine delivers 382 hp and 369 lb-ft, driving the rear wheels through either an eight-speed automatic gearbox or a six-speed manual. Where the Z4 truly sets itself apart is its convertible body style, complete with a retractable soft-top roof.
BMW M240i
BMW M240i & M240i xDrive
Engine Version
B58B30O1
Power
382 hp
Torque
369 lb-ft
Drivetrain
Front engine, RWD/AWD
Transmission
8-speed automatic
The B58 has now featured in not one but two generations of BMW’s most compact rear-wheel-drive model, the 2 Series Coupe. In its current iteration, the 2 Series Coupe relies on BMW’s CLAR architecture, making it a miniature 4 Series Coupe and larger than many enthusiasts would prefer. But it compensates for its size and heft with the B58 punching well above its weight. It uses the most potent variant of BMW’s ubiquitous inline-six, the B58B30O1. Buyers can choose between rear-wheel drive and all-wheel drive, though only an eight-speed automatic transmission is offered. That combination makes it a formidable performer, capable of dispatching the 0–60 mph sprint in 4.1 seconds when equipped with the xDrive system.
BMW X3 M50
BMW X3 M40i
Engine Version
B58B30O1
Power
393 hp
Torque
428 lb-ft
Drivetrain
Front engine, AWD
Transmission
8-speed automatic
Like some of BMW’s other larger models equipped with the B58, the current X3 also features a 48V mild hybrid system. The M50 is the halo model until the next X3 M arrives, and with nearly 400 horses on tap, it’s more than up to the task. The 393-hp inline-six feels effortless, the M Sport suspension adds precision, and the sporty design touches help it stand out in a crowded segment.
BMW M350
The BMW B58 3.0-liter turbocharged inline-six powering the M-performance 3 Series (M340i / M350) remains a gold standard for modern powertrain engineering. Pushing 382 to 392 horsepower and up to 398 lb-ft of torque, this engine pairs effortless low-end grunt with an eager, free-revving top end.
A standard 48-volt mild-hybrid system enhances responsiveness by filling low-speed turbo lag, smoothing the automatic stop-start system, and optimizing efficiency. The powerplant delivers explosive acceleration—routing power through a rapid-shifting eight-speed Steptronic transmission to launch the sedan from 0 to 60 mph in roughly 4.1 seconds.
Beyond pure numbers, the B58 is celebrated for its exceptional thermal management, robust closed-deck block design, and incredible reliability. It provides a refined, muscular acoustic backdrop while maintaining daily driver efficiency, proving why it stands as one of BMW’s greatest modern engine achievements.
BMW 540i
BMW 540i xDrive
Engine Version
B58B30M2
Power
375 hp
Torque
398 lb-ft
Drivetrain
Front engine, AWD
Transmission
8-speed automatic
While the G60 5 Series may have debuted with considerable attention on the electric i5, it was also among the first BMW models to employ the B58B30M2 evolution of the straight-six. This variant loses 7 hp compared to the sportier tune but gains 15 lb-ft, with its power and torque curves retuned for a more relaxed, comfort-oriented character. The 540i’s peak torque arrives at just 1,850 rpm, while maximum power comes in at 5,200 rpm — a setup that prioritizes effortless cruising over outright urgency.
All-wheel drive is standard, and like several other BMW models, a mild hybrid system assists the engine while optimizing fuel economy. The higher torque output suits the 540i’s role as a premium midsize sedan perfectly, demonstrating the B58’s remarkable ability to adapt its character to suit very different vehicles.
BMW 840i
BMW 840i & 840i xDrive
Engine Version
B58B30M1
Power
335 hp
Torque
369 lb-ft
Drivetrain
Front engine, RWD/AWD
Transmission
8-speed automatic
The BMW 8 Series may be one of the brand’s halo models, but in 840i guise — available across coupe, Gran Coupe, and convertible body styles — we find the oldest incarnation of the B58 still in production. The B58B30M1 is a little less powerful than newer versions at 335 hp, but it shares the same 369 lb-ft of torque as later variants, with peak power and torque arriving early at 5,000 rpm and 1,600 rpm, respectively. A sports GT car rather than a pure sports car, the 840i and its xDrive equivalent sit below the M850i and M8 in the lineup. It’s a compelling case for the B58 in a grand touring role, proving the engine is equally at home covering ground in comfort as it is delivering performance on demand.
Boldmen CR4
Boldmen CR4
Engine Version
S58B30T0
Power
408 hp
Torque
450 lb-ft
Drivetrain
Front engine, RWD
Transmission
8-speed automatic
Here we enter the realm of non-BMW-badged cars powered by the German inline-six, starting with the Boldmen CR4. This brand may have passed you by, but German boutique manufacturer Boldmen’s CR4 will probably look familiar — that’s because it is based on the current third-generation Z4 roadster. The CR4’s power and torque outputs are considerably higher, however, thanks to its engine being the S58 version of the B58 family, specifically the S58B30T0.
The S58 is officially the M-tuned variant of the B58, which adds a second turbocharger to produce up to 503 hp and 479 lb-ft. In the CR4, outputs are slightly lower: the base model produces 402 hp and 450 lb-ft, while the available CR4 S steps things up to 492 hp and 516 lb-ft — effectively making this the Z4 M that BMW has declined to build.
Beyond its distinctive styling and S58 engine, the CR4 receives chassis, exhaust, and body modifications that make it a genuine standalone model rather than a badge-engineered Z4. With a choice of 600 colors and a custom handmade interior, the CR4 is a thoroughly bespoke machine. But then, what else would you expect from the founder of Wiesmann?
Toyota GR Supra
Toyota GR Supra
Engine
B58B30C(2020), B58B30O1 (2021-present)
Power
382 hp
Torque
369 lb-ft
Drivetrain
Front engine, RWD
Transmission
6-speed manual, 8-speed automatic
One of the best-known applications of the B58 outside of BMW is the current A90 Toyota GR Supra. Originally launched with less power than the Z4 courtesy of the 335-hp B58B30C version of the engine, it received an upgrade to the 382-hp B58B30O1 for the 2021 model year. Further upgrades came in the form of a six-speed manual gearbox which, while derived from an existing BMW unit, received a number of improvements from Toyota to sharpen shift quality and driver engagement. The transmission plays second fiddle to the B58 engine, though, which delivers its power in a silky-smooth fashion to make the Supra every bit as entertaining as its legendary name suggests.
The Supra is now nearing the end of its production run, and a Final Edition has been unveiled in Japan. It uses the most powerful version of the B58 ever fitted to the model, producing 429 hp.
Ineos Grenadier
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Ineos Grenadier
Engine Version
B58B30C
Power
282 hp
Torque
331 lb-ft
Drivetrain
Front engine, AWD
Transmission
8-speed automatic
The Ineos Grenadier is a rugged off-roader from UK-based Ineos Automotive, conceived as a spiritual successor to the original Land Rover Defender. The resemblance is clear from the outside, but under the hood the Grenadier is anything but old-fashioned, with the B58B30C derivative of the modern B58 engine. Detuned to 282 hp from 335 hp and paired with 331 lb-ft of torque, the engine is calibrated with an emphasis on low-rpm output and long-term reliability — exactly what a serious off-roader demands.
This application of the B58 is paired with an eight-speed ZF automatic and sends power to all four wheels, giving the Grenadier genuine off-road capability. Some markets also receive a B57 turbodiesel option. Buyers needing more hauling capacity can opt for the Quartermaster pickup derivative, though US customers face the chicken tax, which pushes the price into challenging territory. In this application, the BMW straight-six demonstrates just how well it can be adapted to an entirely different kind of vehicle.
Morgan Plus Six
The latest Morgan Plus Six retains the timeless look of a classic British roadster while hiding thoroughly modern mechanicals beneath its aluminum bodywork. The current model produces 335 hp from its B58 engine — channeled through a ZF eight-speed automatic — and benefits from a significantly stiffer structure compared to its predecessor. Weight has been kept in check thanks to Morgan’s bonded aluminum platform, and the carbon fiber hardtop option lowers the center of gravity further still, sharpening the driving experience that has always defined the Morgan brand.
