Lexus has unveiled the world's most powerful hybrid SUV to the Australian public at the Melbourne International Motor Show.

The second-generation of hybrid RX, the RX 450h, will be powered by a larger, all-new V6 3.5-litre Atkinson-cycle petrol engine, along with Lexus' unique hybrid drive system, producing a combined power output of 220kW.

The all-new RX 450h powertrain boosts power by 20kW over the vehicle it replaces, while significant torque increases have also resulted from the new petrol/electric hybrid system.

RX 450h's power increase is achieved while reaping an estimated fuel economy improvement of 8 to 12 per cent* over the previous RX 400h.

The economy savings will see RX 450h achieve fuel figures closer to that of the average four-cylinder family sedan, while delivering the power of a larger capacity engine.

Lexus Australia Chief Executive John Roca said that all-new RX 450h signals the beginning of a new era for the SUV.

"RX 400h set in place the hybrid movement, and RX 450h will solidify the inevitable shift towards a hybrid future," said Roca.

"RX 450h is a representation of Lexus' constant pursuit of perfection, with engineers finding ways to improve the efficiency in virtually every aspect of the hybrid system.

"RX 450h also demonstrates Lexus' commitment to hybrid technology. Now in its second generation it remains the only luxury hybrid available anywhere in the world.

"Lexus is firmly behind hybrid technology and while others continue to discuss the introduction of the technology, we are out there offering real solutions for tomorrow, today," said Roca.