This is the Subaru Advanced Tourer Concept, which gives an idea of what the next-generation Legacy will look like.
It will be revealed at the Tokyo motor show later this month, along with the final production version of the company's BRZ coupe.
The Advanced Tourer Concept features a hybrid powertrain, in which a 1.6-litre petrol engine is mated to an electric motor.
Subaru claims the hybrid set-up is capable of producing the same power output as its 2.5-litre engine but with considerably lower CO2 emissions and much-improved fuel economy. The concept car is also able to travel short distances on electric power alone, which is provided by its lithium-ion batteries.
Also featured on the concept are the latest versions of Subarus CVT gearbox and all-wheel-drive system.
The cabin features a full glass roof, along with high-quality wood and metal trim. There's also a monitor built into the steering wheel, displaying information such as maps, television and other online services.
More performance details will be revealed at the show.
Subaru BRZ coupe
The final production version of the BRZ coupe will also be unveiled at the Tokyo motor show.
Subaru has co-developed the BRZ with Toyota: whose own concept car is called the FT-86. External styling differences between the brands' cars are likely to be limited to bumper, grille and light designs.
The two cars share most parts under the skin, including the rear-wheel-drive chassis and Subaru-developed 2.0-litre four-cylinder 'boxer' engine, in which two pairs of cylinders lie horizontally, punching out like back-to-back boxers.
Subaru hasnt released any technical details, but the Toyota FT-86 is rumoured to have an output of around 200bhp. The BRZ is likely to have similar figures, although the STI-Concept suggests a higher-performance version could also be on the cards.