Thursday, November 16, 2017

New Infiniti QX50 prototype review

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Infiniti QX50 prototype - front
16 Nov, 2017 2:30pm Thomas Geiger

We go for an early drive in a prototype version of the new Infiniti QX50 SUV, featuring the brand's new variable-compression ratio engine

Even more than a decade after launching in Europe, Infiniti, Nissan’s luxury brand, still lacks the reputation of its rivals. And as you have to have something special in order to compete against the Audi Q5, Mercedes GLC and Jaguar F-Pace, rather than brand appeal, Infiniti is focusing on technology with its new QX50 SUV.

We’ve joined Infiniti’s development team to sample the QX50 ahead of its world debut at the LA Motor Show later this month, but more specifically we’re here to try its new variable-compression ratio engine. It’s a world first and will replace the 3.5-litre V6 of the outgoing model; it’s claimed to boost efficiency by about 25 percent while also increasing power and torque. Nissan and Infiniti refer to it a VC-Turbo. 

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How the power and economy improvements have been achieved is by the engine continuously adapting its compression ratio in the range between 8:1 and 14:1; the former for a quick getaway and the latter for restrained driving at lower revs. A mechanical maze of a different links and an electrical actuator controls the pistons, but despite the complex goings-on beneath the bonnet it’s impossible to detect when the engine is doing this from behind the wheel. 

Hit the accelerator and the prototype we were in punches down the road; the engine develops 269bhp and 390Nm of torque, which is about on par with class standards. Performance and response of the engine are impressive and you tend to forget that you’re driving a tiny four-cylinder. 

“We gain up to one second on 0-60mph compared to the four cylinders of our core competitors,” Engine-Chief Shinichi Kiga told us. And after a few very quick stints in the Arizona dessert we have every reason to believe him.

Infiniti's VC-T petrol engine could kill diesels

The new engine is mated to a brand new CVT gearbox. Beloved by the Japanese and largely disliked by the rest of the world it should be the perfect match for efficiency, according to chief engineer Kiga. And understanding the reservations some people have with the CVT Infiniti’s engineering team has spent a lot of time trying to remove the elastic feel it brings to the engine; Infiniti has created eight virtual gears that change fast and smoothly. You still can’t compare it to the comfortable and seamless feeling of dual-clutch automatic gearbox, but overall it is the best CVT we’ve tested so far.

This new powertrain combination is also likely to be the only one offered in the new QX50, at least initially - there’ll be no diesel and no plug-in hybrid or performance-model for some time. It’s a strategy that makes sense; if you want to push a new technology that in Kiga’s view could soon be as common as the direct injection is today.

While the powertrain has already proved its performance, the rest of the QX50 will be kept under wraps until its full reveal at LA Motor Show at end of this month. And while the QX50 will be on US-roads in spring next year, Europeans will have to wait until late autumn. But as Infiniti has already showed us the concept you don’t need a vivid imagination to picture what the finished model will look like. 

Infiniti’s intriguing new variable compression ratio engine makes a promising first appearance in the new QX50. Its response and power is quite impressive and even the CVT gearbox, while still not prefect, is the best we’ve encountered. If this engine really does deliver a 20 to 25 per cent efficiency boost, VC-Turbo technology could be the next big thing for petrol engines and possibly signal the end for diesel. But for the QX50 it will take more than an advanced engine to succeed amongst its strong competitors.


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