Infiniti flagship sedan in the works | report

Infiniti's long-rumoured replacement for the full-size Q45 luxury saloon could be unveiled as early as 2016, according to a new report.

According to Japan's Holiday Auto magazine, the new model will follow the 1-Series rivalling Q30 and new Q60 coupe expected in 2015, along with the new QX70 and refreshed QX80 SUVs in 2016, rounding off five new models expected between 2015-18.

Speaking with an anonymous source, the magazine suggests the "high performance luxury saloon" will appear in concept form by late 2016 or early 2017, with a production model due some time in 2018.

Nissan's luxury brand has not marketed a new S-Class and 7 Series-rivalling full-size saloon since the demise of the third-generation Q45 in 2006, and the report suggests a fourth-generation model had been near completion before being halted by the global financial crisis in late 2008.

Another anonymous source claims to have seen a full-size clay model of the car in mid-2007, which was effectively a four-door version of the Essence coupe concept shown two years later in Geneva.

"We can say that its concept will be based on Cima's (Japan-spec Q45) successor, which was cancelled due to the global financial crisis and also the concept car Essence released the following year," the source noted.

"Of course it has been a while since the crisis, so the design and concept must have been improved."

The report also cites an unnamed Nissan executive, who confirmed that such a model is in the works. "We won't make a car like the Mercedes-Benz S-Class. We will revisit the concept of Essence…"

This suggests a more sporting flavour for the big Infiniti, with the long-nose proportions of the Essence concept likely to result in a model more in line with the Jaguar XJ or Porsche Panamera.

Like the Q30 and next QX70, the flagship saloon is expected to benefit from significant technical input from Mercedes-Benz, with drivetrains sourced from both Nissan/Infiniti and the German carmaker.

Asked why the model is still at least two years away, despite its basic design predating the GFC, the unnamed source cited the need to align with Mercedes' new front-engine, rear-drive platform that debuted with the new C-Class, and will also form the basis for the next E-Class and other assorted derivatives.

"Infiniti had eyes on this and decided to use the new platform with Mercedes technology rather than its own old FR-L (used with the current Q70). The truth is, the negotiation took time and development has finally started," according to the source.

So it may not directly replicate the S-Class, but the flagship Infiniti looks set to benefit from the brand's renowned premium technology at least.

The report also suggests that the new sedan will spawn an Eau Rouge high-performance variant, similar in principal to the recent Q50 Eau Rouge concept, and possibly also using a version of its GT-R sourced 3.8-litre twin-turbo V6 engine.  However, a high-performance hybrid drivetrain is more likely.