It's not often that a car will undergo such a dramatic powertrain change within the lifespan of a single model, but Swedish manufacturer Volvo has announced that it will lop two cylinders off its performance flagships, the Volvo S60 Polestar and V60 Polestar, and return them to market with four-cylinder power.
But though the cylinderectomy will result in two fewer pots and the loss of a litre of displacement, the new Polestar's turbocharged and supercharged 2.0 litre four will rock a healthy 270kW of power at 6000rpm and 470Nm of torque between 3100-5100rpm.
That's 12kW more power than the current model's 3.0 litre twin-turbo inline six, but 30Nm less torque. Balancing out the torque shortfall is a 24kg reduction in powertrain weight and the addition of a Polestar-optimised eight-speed automatic - which replaces the current car's 6-speed auto.
Mechanically, Polestar's version of the 2.0 litre Drive-E engine (which also sees service in T6 variants of the S60 and V60) is based on the same basic block architecture, but uses a unique turbocharger, supercharger, conrods, camshafts and fuel pump.
It also breathes through a low-restriction air filter and optimised inlet tract, and exhales through a 3.0-inch stainless steel exhaust system. Boost pressure is a huge 2.0 bar, or 29psi, and the supercharger helps fill out the torque curve at low rpm when the turbocharger isn't producing boost.
The eight-speed auto takes power to all four wheels via a BorgWarner AWD system, and the new S60 Polestar is capable of blasting to 100km/h in just 4.7 seconds - 0.2 seconds quicker than the current six-cylinder S60 Polestar.
Give it a long enough road, and the 2017 S60 Polestar will hit 200km/h from standstill in 17.2 seconds.
Meanwhile the slightly heavier V60 Polestar wagon will take 4.8 seconds to hit 100km/h, though both will max out at an electronically-limited 250km/h. The Polestar pair will be the fastest Volvo road cars ever made when they go on sale later this year.
Though quicker than the 2015 model, the new four-cylinder S60 and V60 Polestar will also be more frugal. Average fuel consumption is listed at 7.8 l/100km for the S60 Polestar and 8.1 l/100km for the V60 Polestar, reductions of 2.4 l/100km and 2.2 l/100km respectively.
The chassis remains familiar, with Polestar-spec adjustable Ohlins shock absorbers, a carbon-fibre front strut brace, reinforced suspension mountings at front and rear, a unique steering calibration and springs that are 80 percent stiffer than those of an S60 T6 R-Design.
Brakes will be the same Polestar/Brembo package of six-piston front calipers and 371mm two-piece rotors, with sliding calipers and 302mm rotors at the rear.
Wheels still measure 20x8 inches and are wrapped in Michelin Pilot Super Sport rubber, but feature a new spoke design for 2017.
Volvo Australia has confirmed it will bring the new four-cylinder Polestar range to local showrooms later this year, with precise pricing and specifications yet to be announced.
"By any measure these cars are seriously quick,” said Kevin McCann, Managing Director of Volvo Australia.
“When they arrive in Australia later this year people will be genuinely impressed.”
“They are born at the racetrack, but built for the road. They combine Polestar’s 20 years of racing pedigree with Volvo’s inherent pragmatism and engineering heritage.
The end result is two very quick but functional performance cars that can be driven on normal Australian roads every day of the year.”
While Australia was the first market to receive the S60 Polestar back in 2013, Volvo will now expand the number of countries where Polestar cars are sold from 13 to 47, with production doubling to 1500 cars per year.