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  The V6 is combined with two electric motors to produce a total power output of 220kW and push the vehicle to 100km/h in 7.8 seconds. Photo Gallery

• Third-generation RX will launch June 2009.
• The latest RX 450h will gain a 10 percent increase in engine power.
• Lexus RX 450h is bigger all round.

Lexus has released details of its cleaner and greener RX 450h hybrid SUV.

The third-generation RX (and second-generation hybrid SUV) will be launched in Australia in June.

The RX 450h features a 10 per cent increase in engine power, a 28 per cent reduction in combined cycle fuel consumption, a 30 per cent improvement in cold weather fuel efficiency and a 23 per cent reduction in CO2 emissions.

RX 450h's new 2GR-FXE petrol engine employs the Atkinson, or high-expansion, cycle for improved efficiency. It has a higher compression ratio than a conventional Otto Cycle engine and keeps the exhaust valves closed until the end of the expansion stroke for maximum combustion effect.

The expansion stroke is extended, converting more of the combustion energy into torque on the crankshaft.

Lexus has combined the Atkinson Cycle with direct ignition, Quad-Cam Multi-valves and dual Variable Valve Timing with intelligence (VVT-i) to optimise efficiency.

Fuel economy and emissions are further improved by cooled exhaust gas recirculation, exhaust heat recovery, reduced hybrid transmission friction losses and a new power control unit.

The V6 is combined with two electric motors to produce a total power output of 220kW and push the vehicle to 100km/h in 7.8 seconds.

Fuel consumption is 6.3 litres per 100km, while CO2 emissions are down from 192g/km to 148g/km, which is less than a Toyota Corolla (175g/km).

Lexus Australia chief executive John Roca said demand for Lexus hybrids had risen steadily since the introduction of the RX 400h SUV in 2006.

"The proportion of total Lexus sales captured by hybrid is now 12 per cent," he said.

"Lexus expects hybrid sales, as a proportion of total sales, to continue to grow steadily as we launch new product, the first of which is the new RX 450h in July."

Total RX sales are down 14 per cent to 880 so far this year, which is better than most in the luxury SUV category which is down 24.3 per cent.

The new RX 450h is bigger all round at 15mm longer, 40mm wider, 10mm higher and 25mm longer in the wheelbase while retaining its 5.7m turning circle.

It rides on new double wishbone rear suspension replacing the struts used in the RX 400h.

Allied to the increase in wheelbase length and track width, this is claimed to reduce body roll and pitch by up to 40 per cent.

The front suspension has also been extensively re-engineered, with new shock absorbers, optimised springs, anti-roll bar and component geometry. Electronically Controlled Air Suspension gives the driver a choice of four vehicle height settings over a 60mm range and automatically lowers when travelling at speed to optimise aerodynamic performance, stability and fuel economy.

Inside, there is a new remote touch control navigation system which operates like a computer mouse. It operates the vehicle's audio, navigation, ventilation, phone and set-up systems. The new RX also features head-up display which screens key driving data in the driver's line of sight at the base of the windscreen.

The information presented includes vehicle speed, turn-by-turn navigation instructions, audio information and Adaptive Cruise Control and Pre-Crash Safety system status. The navigation system has a 40Gb HDD capacity.