SPY PICS: 2017 Subaru Impreza sedan spotted

Subaru's next generation Impreza has been teased at this year's Tokyo motor show via a slinky five-door hatchback concept.

Now, the production model – as a sedan – has been seen on public roads in Japan. The new model is expected to grow slightly without suffering weight penalties via a global (SGP) platform, while also sporting a new 1.6-litre direct-injected turbo engine that will increase performance while reducing both fuel consumption and exhaust emissions.

Sounds like a familiar formula, but the new Impreza that is expected to appear some time in 2017 will benefit from the new platform that will have far-reaching influences on most Subaru models, improving overall function and efficiency while allowing the Impreza to remain within a similar size envelope.

The Volkswagen Golf/Mazda3/Toyota Corolla competitor is expected to run on a slightly bumped-up wheelbase, similar to that of the Tokyo concept, which measured 2670mm against the current model's 2645mm. In hatchback form at least, overall length could be pegged back slightly, from 4420mm now to 4400mm in the new model. The concept's 1880mm width is the only dimension to vary significantly from the current model, which measures 1740mm.

And while we're pretty familiar with the Tokyo concept and its likely similarities with the production 2017 Impreza hatch, the realities of the sedan version have so far been speculative only.

Now, as these spy photos graphs show, it's clear the four-door Impreza will also follow the same basic themes as the show car. The disguise-clad test mule indicates that the concept's external architecture will be generally replicated in the sculpted side panels and the bulbous shaping above the front wheel arches, as will the BMW-style kick in the rear side windows.

The front end is not so easy to speculate on, but there's no reason suggesting it will vary greatly from the heavily-sculpted concept. Similar interpretations could be applied to the rear end, although it looks pretty clear the overall effect will be, in typical sedan style, more conservative.

Word is also circulating that Impreza production, initially expected to take place in the company's plant in Indiana U.S.A, will continue to take place in Japan, although the next generation XV Crosstrek model is expected to be US-built.

The next Impreza is expected to make its first appearance in Japan in late 2016, which hints at an Australian launch in the first half of 2017. A plug-in hybrid variant is expected to follow in other markets not long after, although it's not clear whether it will come to Australia.