Volvo's Polestar tuning division isn't exactly a well-known powerhouse like the AMG or M-divisions. Still, the brand has recently built some of the most impressive four-cylinder drivetrains on the market. Polestar versions of the S60 and V60, for example, make 362 hp from a twin-charged four-cylinder engine. Now, Volvo is rumored to be working on Polestar versions of the S90 sedan and V90 wagon. The most powerful T8 versions of these cars use the same twin-charged engine to make 450 hp.

Volvo says that Polestar versions would have a larger electric motor than the current 87 hp motor that drives the rear wheels on T8 models. This twin-charged hybrid drivetrain could produce as much as 600 hp, easily allowing Volvo to compete with V8-powered models from AMG and M. Volvo's R&D chief Peter Mertens has confirmed to Motor Trend there will be Polestar versions of both cars, although there is currently no plan to bring them to the US. If Volvo does actually build a 600-hp car, it could well make it to the US. Even Mertens says that he would like to see them on sale stateside.