There's a rumor going around Japan that the Subaru Viziv 2 concept car revealed at this year's Geneva Motor Show previews the next-generation Forester. But our sources point in a different direction.

Given that the latest Forester has been on sale barely more than a year, and that the smaller XV Crosstrek is just more than 2 years old, we can safely say the Viziv 2 is not a replacement for either SUV.

Nor does it preview the new Outback, which is expected to debut at the New York Auto Show in April. A new Legacy sedan and Outback are scheduled to be on sale here almost simultaneously early in 2015.

Compelling evidence about the concept's secrets came from a source close to Subaru who tells us this sharp-looking crossover hints at what a new, smaller SUV will look like, while at the same time suggesting the shape a much larger Subaru SUV will take.

This is Subaru's new design language for SUVs and we can expect to see a lot more of it in future models. While our source remained tight-lipped about the new smaller model, he did expand on the larger one.

So how big will it be? "Try reinterpreted Tribeca territory."

Just as the underperforming Tribeca is being phased out, news of a new interpretation makes perfect sense. Only this time, Subaru has to get the package right. It has to look good, deliver enough power, and offer class-leading fuel economy and CO2 emissions.

And if the Tribeca replacement -- it will probably get a new name to differentiate it from the outgoing sales disaster -- borrows lines from the Viziv 2, then it is definitely heading in the right direction. This concept is without doubt the best-looking crossover design we've seen from Subaru.

Despite the fact it incorporates just four seats, we're told the Viziv 2 show car accurately previews the design direction of a bigger new SUV.

More critical to the new crossover's success than its styling will be its powerplant. That's why the current Tribeca's thirsty 3.6-liter six-cylinder boxer engine is being considerably downsized.

But don't think that the new SUV will want for power. "The radical new engine will offer plenty of poke," says our source.

In realizing that engine, Subaru will lean heavily on its relationship with Toyota, which blossomed with the Scion FR-S/Subaru BRZ collaborative effort.

This new crossover will bring together two of the industry's most advanced engine technologies: the world's only boxer diesel engine, and Toyota's tried and proven THS-II hybrid system.

Although the concept was powered by a 1.6-liter horizontally opposed four-cylinder direct-injection turbo boxer engine, we understand the production model will be powered by the 2.0-liter turbo-diesel boxer fitted to the Outback and Forester, in which it generates about 148 hp and a beefy 258 lb-ft of torque from just 1800 rpm.

To produce the ideal combination of sufficient torque and class-leading mileage and emissions for the larger crossover, Subaru engineers will take Toyota's hybrid system and employ in-house knowhow honed on the XV Crosstrek hybrid project to create a plug-in hybrid.

That's right, the new Subaru SUV will be the world's first turbo-diesel boxer plug-in hybrid. So you can expect a strong dose of extra torque with emissions clearing 158 g/km. To clean up emissions even further, the crossover will incorporate a diesel particulate filter to minimize CO2 and other emissions.

Also previewed by the Viziv 2: The groundbreaking powertrain incorporates one front electric motor and two rear motors, all charged by a lithium-ion battery. As Subaru promised when it revealed the Viziv 2, the independent rear motor-driven symmetrical AWD system "points the way to a future generation of Subaru technology" and will offer "superb driveability, based on the low center of gravity and superior weight distribution."

At last, a stylish Subaru crossover by late 2017 that will offer world-leading technology and a totally new driving experience -- or at least that's what our insider hints at. If the promise meets reality, then we have something to look forward to.