LEXUS LAUNCHES WORLD’S MOST EFFICIENT LUXURY SUV
‘Brilliant’ and ‘Remarkable’ are often over-used words, but in the case of the new Lexus RX 450h they perhaps short-change this new luxury hybrid SUV.
With 290kW of power from the petrol/electric engines, the RX 450h is now the world’s most powerful and efficient luxury SUV.
Consuming as little as 6.4l/100kms of fuel and emitting 150 grams of C02, the RX 450h delivers V6 performance plus the space and practicality of an SUV… yet sets fuel economy and efficiency figures closer to that of small four-cylinder hatchbacks.
In fact, thanks to its fuel efficiency, the luxury RX 450h is Australia’s first hybrid to be exempt from the Federal Government’s Luxury Car Tax (LCT) – equating to a $4,000 RRP saving. To achieve this exemption, the RX 450h had to deliver combined cycle fuel economy under 7.0-l/100kms…it’s 6.4l/100kms easily eclipsed the required figure.
What You Get
There should be no doubt about the commitment to Lexus Hybrid Drive technology – the LX 450h, designed as a hybrid from the outset, is the company’s fourth hybrid model and in terms of technology, debuts many remarkable world-firsts. Here is a sample:
- The world’s first hybrid system to use an Atkinson Cycle V6 engine
- A cooling system for exhaust gas re-circulation to improve fuel economy and reduce emissions
- An exhaust heat recovery system to reduce engine warm-up time – which improves fuel economy
- Regenerative braking at all four wheels
- A self-contained transaxle cooling system to reduce bearing friction losses – higher power transmitted to the wheels and improved fuel efficiency
That’s just scratching the surface of the staggering technology Lexus has employed with the RX 450h.
But first this is a Lexus, so the three-model range boasts extensive luxury and convenience features, the attention to detail and manufacturing quality is meticulous and – helped by an upgraded CVT transmission and innovative new suspension design – the driving dynamics on all road surfaces are superb.
Under The Hood
This is where it gets complex. To be accurate, the Lexus RX 450h has a petrol-electric series and parallel hybrid powertrain consisting of:
- A specially-developed 3.5-litre V6 Atkinson Cycle V6 petrol engine
- A generator and 123kW electric drive front motor, reduction gears to the front axle and a continuously variable transmission that doubles as a power-split device. Some of the engine’s power output is transmitted to the electric drive motor, via the generator, as supplementary power for vehicle acceleration
- A second 50kW AC permanent magnet motor powers the rear wheels during take-off and acceleration.
In an Atkinson Cycle petrol engine (also known as the high-expansion cycle) the expansion stroke of the pistons is actually longer than the compression stroke and this is claimed to harness more torque on the crankshaft than a conventional (Otto cycle) engine design. To this fundamental shift in engine design philosophy, Lexus has added direct ignition and quad-cam multi-valve cylinder heads with variable valve timing.
The petrol engine delivers 183kW of power at 6000rpm and peak torque of 317Nm at 4800rpm. The Hybrid electric motors combined produce 220kW. Lexus says the combined power of the petrol engine and electric motors is 290kW.
The Interior
Lexus technology hits don’t stop with the drivetrain. The RX 450h debuts an electronic climate control system with a compressor that operates without the need for the petrol engine – this contributes to a one per cent fuel economy gain.
Otherwise the interior is similar to the petrol-only RX 350 (except for the ECO feature gauges that replace the usual tachometer).
We like the center console-mounted Lexus Remote Touch system which operates the navigation system in such a way that reduces the need for drivers to divert their attention from the road ahead.
Front seats are nicely shaped and supportive with electronic adjustment. The beautiful timber/leather steering wheel offers electronic adjustment for reach and rake.
Rear seat accommodation is excellent with legroom amongst the best in this segment.
There is a reversing camera, side-parking camera, heads-up display and more.
Exterior & Styling
Although evolutionary, the styling of the RX 450h is quite different to the RX 350.
There are a number of design elements unique to the RX 450h that distinguish it from the RX 350 – the silver grille, 15-spoke 19-inch alloy wheels, blue accents for the headlights and fog lights to name a few.
Overall the aim was to achieve the class-leading co-efficient of drag of just 0.33Cd and minimal noise intrusion to the cabin. A new undertray produces a venturi effect to assist with downforce and promote even airflow.
Acoustic glass is fitted and a new windscreen mounting system reduces the gap between body panels and glass.
On The Road
Lexus was happy for us to put the RX 450h through its paces at Sydney’s Eastern Creek Raceway in back-to-back tests with its predecessor to demonstrate the improved ride and handling from the all-new suspension system. The system includes fascinating reverse-taper front springs and other enhancements which deliver significant reduction in body roll and dive.
Over a mixture of urban and rural roads – including some lengthy stretches of dirt tracks – around Sydney’s Hawkesbury River, the RX 450h impressed with its performance and poise, but especially its refinement and quietness at all speeds on all surfaces.
Lexus engineers made six world tours to make sure the RX 450h met expectations in markets everywhere. As well as high performance testing at Germany’s Nurburgring (naturally), testing also took place in Italy, North America and New Zealand.
One area that is significantly better that the previous RX is the CVT – this is truly seamless in the transition between electric and petrol power.
Challenges
We love all the technology included in the RX 450h – but is that passion shared by luxury SUV buyers? Does your average luxury SUV buyer really care that they can save the equivalent of eight Melbourne-Sydney jet flights worth of CO2 emissions each year by switching to an RX 450h?
Certainly they should be thinking that way and Lexus says pre-launch orders are strong and points to its global success as a marketer of hybrid vehicles. Verdict
This is a stunning vehicle, by any measure. Even if you discount the plant-saving technology of the RX 450h, you still can’t ignore the superb driving dynamics, wonderful packaging, beautiful interior and sublime build quality.
The Competition
Lexus played an ace by gaining the LCT (Luxury Car Tax) exemption. Entry to the RX 450h range is the Prestige model priced at $89,900. Next-up is the Sports at $96,900 and the range-topper is the Sports/Luxury at $107,900.
Realistically, that puts the RX450h head-to-head with some BMW X5. Mercedes-Benz ML-Class, Volkswagen Touareg and Audi A7 models.
What’s the price for saving the planet? Time will tell.
