Lexus NX gets ground-breaking turbo tech to climb SUV ladder

Rob Maetzig

The Lexus NX200t Limited gets a stack of luxury options inside and the world's first turbocharged Atkinson Cycle engine under the bonnet..

Last year when the Lexus NX was launched in New Zealand it was only available with petrol-electric hybrid technology, and it came in for some criticism for this.
At issue was the fact that the powertrain under the bonnet of the NX300h wasn't particularly new. Its 2.5-litre petrol engine with hybrid drive was the same as that already aboard other Lexus and Toyota product, so in that regard the NX wasn't seen as particularly groundbreaking new product.
The fact the NX is loosely based on the Toyota compact SUV the RAV4 also added to a fairly lukewarm reception from some motoring critics.

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However, at the time this criticism was being voiced it was known that a special petrol version was in the wings.
That vehicle has now arrived - four of them actually. The three-model NX 300h hybrid range has been joined by a quartet of models all powered by an engine that is not only Lexus' first turbocharged petrol unit, but which is also the world's first Atkinson Cycle engine to be turbocharged.
Traditionally, petrol engines operate to the four-stroke Otto Cycle involving intake, compression, combustion and exhaust piston strokes, with each of these strokes of equal length and timing.
Years ago British engineer James Atkinson modified all of this by developing engine technology featuring variable length piston strokes and delayed closing of intake valves. These changes, known as the Atkinson Cycle, improved an engine's thermal efficiency which meant they didn't use as much fuel - but the downside was the engine wasn't as powerful as the Otto Cycle units.
In more recent years the Atkinson Cycle engines have been found to work very well as part of petrol-electric hybrid technology, because the electric motors have been able to compensate for the lack of engine power.
But now Lexus engineers have developed ways to make Atkinson Cycle engines more powerful anyway - they have developed intelligent variable valve timing that can so widely advance and retard engine timing they can operate in both the Otto and Atkinson cycles. And they have added very advanced twin-scroll turbocharging to help take the fullest advantage of that.
All this technology is part of the 2.0-litre four cylinder engine under the bonnet of the Lexus NX 200t. It features both VVT-i (intelligent variable valve timing) and VVT-iW (the W stands for wide), the fuel injection system is turbo specific, and the turbocharger itself only operates at the boost pressure necessary to develop the engine torque required at any particular time.
This twin-scroll turbo synchronises itself with the vehicle's electronically controlled six-speed automatic transmission, and between them they work to ensure there's an increase in turbo boost pressure just before any gear up-shift so boost can be exactly what is required - which in turn preserves fuel economy.
Technically it is all very impressive, and what is even better is there's no need for any special driver input - you simply drive the car. Little wonder then that this new powerplant will be introduced into other Lexus and Toyota models in the future.
For this first Lexus use, the new engine offers 175 kilowatts of power and is aboard four grades of NX - a NX200t two-wheel drive,  and three all-wheel drive versions badged AWD, F Sport and Limited.
The F Sport is said to be the NX that makes the best use of the engine thanks to various performance-oriented features including adaptive variable suspension and an extra Sport+ option in its Drive Mode system. We haven't that model yet - our first experience with the engine has been with the most luxurious NX, the $94,900 Limited.
Thanks to all that turbocharging and direct injection, the NX200t's engine is more powerful than the hybrid anyway, and performance is the same no matter whether it is the F Sport or the Limited. Whereas the hybrid offers 145 kW of power and 210 Nm of torque, the latest model has 175 kW and 350 Nm, with the torque maxing out at a low 1650 rpm through tio 4000 rpm. That's sufficient to let the NX accelerate to 100 kmh in 7.1 seconds which is impressive for an SUV.
Just like as is the case with the hybrid versions of the NX, the Limited carries a high level of specification - as it should for its price. The upholstery is full leather, there's a nice wood finish to the interior, and luxuries include a world-first touch sensitive overhead LED light system which does away with switches above the centre console. Instead, those in the front seats can turn on personal and map lights with aq simple handc swipe across the smooth surface.
The centre console itself houses a lateast-genration Remote Touch Interface system that features a touchpad that is operated like a smartphone to access audio, climate control, satellite navigation and other vehicle settings and information. In theory this is a great system, but personally I find it a little too touchy for my liking. What I do like though a a wireless charging tray that can be used to charge cellphones and other wireless devices.
Safety assumes a high priority with this car, with standard features including a panoramic view monitor which gives a birds-eye view of the car, which is a boon when parking. The vehicle also has rear cross-traffic alert, blind spot monitoring, and dynamic radar cruise control which uses milliwave radar to ensure the NX keeps a safe distance from the vehicle in front. It's all very useful.
But all of these features are also aboard the hybrid NX. The big difference between that SUV and this one therefore is that new-age turbocharged 2.0-litre engine, which is a beauty. At times it can sound a littlethrashy, but there's no doubting its performance ability. We're looking forward to seeing it aboard more Lexus and Toyota product in the future