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BMW Is Pushing its B58 Straight-Six to New Peaks

BMW is in the process of upgrading the B58 straight-six and it could spread across the lineup

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BMW’s B58 straight-six is found in a number of non-M models ranging from the base X5 to cars like the BMW M240i and even the Toyota Supra. Power output for most models comes in at 335 horsepower while the version in various M40i models tops out at 382 ponies. Now, however, a new version of that B58 is in the works, and it will push the B58 designation to all-new heights.

The Upgraded B58 Straight-Six – What You Need to Know

BMW Is Pushing its B58 Straight-Six to New Peaks
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Now, we’re learning that BMW is currently updating its widely used B58 straight-six, and that means more power is coming.

The B58 engine, in its current capacity, is responsible for providing motivation to a number of vehicles, including cars like the X5 40i, the X7 xDrive 40i, 540i, 640i, 740i, and even the 840i - in all of which it delivers a reasonable 335 horsepower. A tweaked version of it that’s worth 382 horsepower is found in the Toyota Supra, BMW Z4 M40i, M340i, X3 M40i, M440i, and the M240i. This new report from BMW Blog claims that the upgraded version will carry the designation of M58B30M2 and in its base form, the 3.0-liter mill will be food for 370 horsepower. Of course, it should be noted that the current B58 has proven to be much more powerful on the dyno (335 horsepower at the wheels), so there’s a chance that the new engine will be worth more than the expected 370 ponies.

BMW Is Pushing its B58 Straight-Six to New Peaks
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The BMW Z4 is probably going to be discontinued after the 2025 model year, but an important update is expected to happen in 2023.

The new B58 will also replace the engine found in the Supra, Z40, and various M40i models across the lineup. While no definitive numbers are given for that version of the engine, the outlet speculates that it could be advertised at around 400 horsepower. It would also come with various upgrades, including improved thermal management, revised induction for better responsiveness, and other minor enhancements to improve efficiency. A larger turbocharger and revised intake manifold are said to be the prime among the fresh upgrades.

BMW Is Pushing its B58 Straight-Six to New Peaks
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This upgraded engine will continue to power models like the BMW X5 xDrive 40i, 540i and even the 840i, but wait, there’s more!

As for what models the new B58 will land in first, that’s a mystery, but the updated M540i and 740i are the most obvious ideal candidates. The Toyota Supra and BMW Z4 are said to be on the chopping block post-2025, but a sizeable update coming in 2023 means they could also get the updated B58 for their last couple of years on the market.

Source: BMW Blog

Robert Moore
Robert Moore
Editor-in-Chief and Automotive Expert - robert@topspeed.com
Robert has been an auto enthusiast his entire life. He started working cars at a young age, learning the basics from his father in the home garage on the weekends. As time went on, Robert became more and more interested in cars and convinced his father to teach him how to drive when he was just 13 years old. Robert continued working on cars in his free time and learned as much as he could about engines, transmissions, and car electrical systems, something that only fed his curiosity more and eventually led him to earn a bachelors degree in automotive technology with a primary focus on engine performance and transmission rebuilding.  Read full bio
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