Under the scooped bonnet lives a version of Subaru's 2.0-litre direct injection turbocharged four-cylinder boxer engine that's capable of delivering 221kW of power and 400Nm of torque to all four wheels. That places it above the 197kW/350Nm output of the 2.0-litre Aussie WRX and almost line-ball with the 221kW/407Nm available in the local 2.5-litre WRX STI.
Before we get too jealous of those living in Japan, the S4 won't be available with a manual shifter. Instead, Subaru is only offering the S4 with a continuously variable transmission (CVT). Eight "gears" are available, both automatically and via paddle shifters, if the SI-Drive selector is shifted into Sport# mode.
The S4 features torque vectoring control and split five-spoke 18-inch alloy wheels shod with 225/45 rubber as standard. Aside from the new alloys and the matte metal-look wing mirror caps, the S4 isn't that aesthetically different from WRXes available outside of Japan — the lower LED driving lights seen above are factory accessories.
For the S4, Subaru has added a bunch of safety technology to the WRX range for the time, including the latest generation EyeSight system, which now has a wider field of vision and the ability to see in colour. Lane keeping assistance, brake light recognition and pre-collision reverse throttle management also make their debut. Two new paint schemes are also available: blue pearl (above) and crystal white pearl.
The new WRX S4 is now available for sale across Japan. Subaru Australia has ruled out offering the S4 model, stating that car - and its engine tune - are confined to the Japanese market.
Simultaneous with the S4's unveiling in its home market, Subaru has also launched the domestic version of the current generation WRX STI. Unlike the STI available in Australia, the Japanese STI features a 227kW/422Nm turbocharged 2.0-litre engine. Power is sent to all four wheels via a six-speed manual transmission and a driver adjustable centre differential.