The BMW B58 turbocharged inline-six has been with us since the 2016 model year, and the most potent 380-horsepower version of the engine was unveiled back in 2018. When the new Z4 and jointly-developed Toyota Supra arrived on the market not too long ago, there was an interesting discrepancy between the powertrain choices of the two highly similar vehicles. The Z4 M40i came with with the most powerful version of the B58, the 380-horsepower variant (or 382, or 388, depending on your source) shared with other M40i M Performance models like the M340i and X3 M40i, the latter of which was upgraded to 380 horsepower for the 2020 model year. The Supra GR, on the other hand, was launched with the B58B30C, developing 335 horsepower.
Perhaps not unexpectedly, this has been changed for the 2021 model year. Going forward, the Toyota Supra GR will use the 380-horsepower B58 like various other BMW models. The torque rating between all of the B58 engine variants being discussed here is the same—369 pound-feet from 1,600–4,500 rpm. And while the four-cylinder Z4 (sDrive30i) is a great car on its own merits, something like the Toyota Supra needs big power (and torque) to fill the role and effectively follow up on the success of its 1990’s MkIV predecessor.
It didn’t take long for a trustworthy outfit in the automotive world to dyno a 2021 Supra, and you may or may not be surprised with the results. As has been the case with other BMW and BMW-powered cars, the 2021 Toyota Supra put down more power than it’s advertised as having. To revisit the specifics, the BMW B58M30O1 used in the upcoming 2021 Toyota Supra is quoted as having 382 horsepower and 368 pound-feet of torque according to Toyota. In the real world through, it seems like at least 400 horsepower, as per Car and Driver.
The specific results make a strong case for the 2021 Supra, and any BMW using the top tier B58. On a Dynojet dynamometer, the 2021 Supra put down 388 horsepower and 421 pound-feet worth of twist. Setting torque aside (the car and engine have plenty, regardless) because it’s tough to get an accurate reading at low revs with a torque-converter auto like the ZF eight-speed, accounting for drivetrain loss means the B58 in the 2021 Supra is realistically developing more than 400 horsepower at the crank. Pre-production press car fluke? Perhaps, but it’s not the first time it’s happened with a BMW engine, especially in the turbo era we now found ourselves in.
Either way, that’s a lot of power, and a safe margin above what the engine and car are actually rated as having. We’ve long known BMW’s turbo six-cylinder engines make great power, and with a few rather inexpensive tweaks and supporting modifications, it’s not hard to extract significantly more out of one—granted you’re up to date on maintenance. But while the initial BMW-powered Supra was also tested as being more powerful than advertised, the current model edging closer to 400 horsepower is all the more encouraging. It could only be a matter of time until we’re seeing incredible runway drag race builds with four-digit power figures.—Alex Tock
[Photos courtesy BMW AG, Toyota Motor North America.]