The split is expected to begin with the arrival of the 2012 Impreza. There have been reports in recent months suggesting that the current WRX sedan and hatch will sell alongside the all-new Impreza range.
Now, new reports point to a 2014 unveiling for an all-new WRX, built on a unique platform completely separate from the four- and five-door Impreza variants.
“Apart from a few nuts and bolts, every part on the WRX will be unique. Even the engine and body," an unnamed source reportedly told US magazine Motor Trend this week.
"Obviously the WRX’s platform will be inherited from the new Impreza, but it will be radically modified and significantly shortened.”
The source reportedly added that the separation will allow Subaru to reduce the level of 'over-engineering' in the regular Impreza, while focusing on a shorter wheelbase and lightweight construction for the WRX.
It is also believed that Subaru is considering a return to the World Rally Championship, and Motor Trend's source describes a new WRX that has been developed from the ground-up to take back the company's rally superiority.
Although the carmaker has yet to offer any official word on a next-generation WRX model, Subaru President Ikuo Mori confirmed at a recent shareholder meeting that "a new sporty car" will arrive in 2014.
With Subaru's new Toyota-partnered coupe confirmed for a mid-2012 launch, it is possible that Mr Mori's comments are in reference to a new WRX.
If true, the move could be influenced by partner Toyota, which launched the original Supra as part of the Celica range. In following generations, the Supra become a high-powered rear-wheel-drive coupe, while the Celica was offered in various outputs and layouts over the years.