Few concrete details are known about the new car, but we do know that the WRX S4 will be equipped with the latest version of EyeSight, which uses colour stereo cameras to detect pedestrians and vehicles. The WRX and WRX STI available in Australia isn't available with EyeSight.
Subaru is also promising that the new car will have "superior environmental friendliness" and "high-quality feel". According to the WRX S4's teaser website, the new car will equipped with a Blue Boxer engine. It's unknown if this engine differs to the 197kW/350Nm 2.0-litre turbocharged direct injection unit employed in the local WRX.
At present neither the fourth-generation WRX nor the WRX STI are available in Japan, with only the previous generation WRX STI on sale there. So, it's possible that the WRX S4 is just a domestic market version of the fourth-generation version WRX upgraded with the company's latest technology.
According to Subaru, the S4 nameplate represents the new car's sports performance, safety performance, smart driving and sophisticated feel. We're not entirely sure how Audi feels about this, but there's every chance that Subaru's use of the S4 badge will be restricted to the home market.
In the land of the rising sun the current generation Impreza is dubbed Impreza Sport in hatchback guise and Impreza G4 for sedan variants.