The fifth-generation Toyota Supra has nearly reached the end of its lifecycle, according to a recent rumor, and it's allegedly going out with a bang. Japanese magazine Best Car learned that the coupe will spawn a 550-horsepower, GRMN-badged model before retiring.

Without citing sources, the publication reported that the final and most powerful evolution of the current-generation Supra will make its debut by the end of 2023 and go on sale the following year. It's too early to tell whether the model will only be available in select markets, or if it will be sold globally. Regardless, the enthusiasts who get their hands on one will be in for a treat: Power for the Supra GRMN will reportedly come from a twin-turbocharged, 3.0-liter straight-six engine shared with the limited-edition BMW M4 CSL introduced in 2022.

Part of the S58 family of engines, the six makes 543 horsepower and 479 pound-feet of torque when bolted between the M4 CSL's fenders. Best Car pegged the Supra GRMN's output at 550 horsepower, though that could be a conversion error; 550 pferdestärke (the German way of measuring an engine's output) represents almost exactly 543 horsepower. We're also not discounting the possibility that, if the rumor is accurate, Toyota will make changes to the engine in-house. An eight-speed automatic transmission should be the only option offered.

For context, the most powerful engine available in the street-legal Supra is a 3.0-liter turbocharged straight-six rated at 382 horsepower and 368 pound-feet of torque. That's enough for a 3.9-second sprint from zero to 60 mph and a top speed that's electronically limited to 155 mph.

While this is pure speculation, we're guessing Toyota won't simply drop a more powerful straight-six in the Supra's engine bay, close the hood, and call it a good job well done. We expect several trim-specific add-ons inside and out, including a full body kit, will set the GRMN apart from the standard Supra. Toyota reserves the GRMN name for its most hardcore models, so the Supra would have a lot to live up to.

Toyota hasn't commented on the rumor, and it hasn't announced what the future holds for the Supra. If the report is on the mark, we should learn additional details about the final version of the Supra — and, hopefully, about the model's successor — in the coming months.

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