LA MOTOR SHOW: Infiniti teases QX50

Nissan luxury car brand Infiniti has teased the final production version of its crucial new QX50, which will do battle with the Mercedes-Benz GLC, BMW X3 and Audi Q5.

The new Japanese mid-size luxury SUV will make its debut at the 2017 Los Angeles motor show next week (November 29) and this teaser image shows its multi-lens LED headlight cluster and grille, revealing strong visual similarities with the Infiniti QX50 concept revealed earlier in the year.

At the same time, Infiniti has also announced it is ready to release a turbo-petrol 2.0-litre four-cylinder engine featuring variable compression ratio technology -- a world-first for a production vehicle – and it could debut in the QX50.

What does variable-compression mean to the average motorist? In a nutshell, you get the power of a big six-cylinder (200kW/390Nm) with the efficiency of a compact turbo-diesel engine, potentially as low as 6.0L/100km.

The new engine is expected to replace Nissan's famous 3.5-litre V6 engine family and will find its way into other Infiniti cars.

It's likely Nissan and potentially even its sister brands Renault and Mitsubishi will also gain access to the technology in due course.

There will be many people wondering why Infiniti doesn't just expand its adoption of electrified powertrains -- it is working on EV technology -- instead of developing expensive new tech for combustion engines.

The answer is fossil-fuelled cars will be around for many decades to come in some form.

Car-makers are having to meet increasingly strict CO2 emissions targets, so in one corner you've got the likes of Mazda working on petrol engines that run like diesels, dubbed SKYACTIV-X, and now Infiniti is doing its own ultra-efficient petrol engine with variable-compression ratios.

Infiniti revealed a prototype for the VC-Turbo (Variable Compression ratio) engine in mid-2016 after years of development, and it works by utilising a multi-link system to "seamlessly raise or lower the stroke of the pistons, detecting the car's driving condition and driver inputs, and instantly selecting the most suitable compression ratio," according to Infiniti.

The compression ratio of the engine can be altered between 8:1 for high power output, to 14:1 for enhanced fuel efficiency. It means more moving parts and complexity inside the engine block, but in practice drivers won't even know the techno-gubbins are working. Except for the fact the car accelerates better while using less fuel when cruising.

"VC-Turbo technology is a step change for Infiniti," said Roland Krueger, president of Infiniti. "It is a revolutionary next-step in optimising the efficiency of the internal combustion engine."

For its production debut, it's expected to be mated to a CVT or continuously variable transmission.

"As with all Infinitis, we have been inspired by our desire to drive, expressed with power and artistry. With this all-new model, inspiration comes from striking the perfect balance between lust and logic," gushed Alfonso Albaisa, senior vice president of global design at Infiniti.

"At a glance, seamless and sculptural, getting closer to the car reveals an ingenious blend of proportion and space," he said of the QX50.

Power output for the first new-generation engine will be around 200kW and 390Nm, but the company has previously admitted that other engine sizes and configurations were under consideration.

We can only imagine what a V6 with this technology would be like. A next-generation Nissan GT-R with VC-Turbo and electric motor boosting could be interesting.

Of course, it's also possible the new VC-Turbo engine could debut in the flagship luxury sedan that Infiniti will unveil at the Detroit motor show in January alongside an all-new battery-electric sports car.