The new Lexus RX 450h introduces second generation Lexus Hybrid Drive technology, following on from the 2005 launch of the original, ground-breaking RX 400h. This new, full hybrid SUV Lexus Hybrid Drive takes the RX range into its third generation as the world's best selling luxury SUV.

The new model perfectly expresses the kaizen and forward-thinking inherent in Lexus's L-finesse design philosophy. While many rival manufacturers are yet to produce a first generation hybrid, Lexus has drawn on more than a decade of experience in full hybrid powertrain technology to bring about improvements in every aspect of the vehicle's Lexus Hybrid Drive system.

As a result, the RX 450h's real-world efficiency has been significantly improved, with 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 an unparalleled reduction in CO2 emissions.

Lexus Hybrid Drive

Unlike mild hybrids, which use supplementary electric motor power simply to boost the performance of the petrol engine, the RX 450h is a full series/parallel hybrid, capable of operation in both petrol and electric modes alone, or in a combination of both. It combines the fuel efficiency and reduced emissions benefits of a series hybrid with the acceleration benefits of a parallel hybrid.

It shares the RX 400h's drivetrain configuration of a series/parallel hybrid system, employing a highly efficient V6 petrol engine and two powerful electric motors working in tandem to provide an 'intelligent' four-wheel drive capability.

Total power output is 295bhp (299 DIN hp), enabling a top speed of 124mph and nought to 62mph acceleration in 7.8 seconds. Conversely, the RX 450h has the lowest fuel consumption of any premium SUV model with a combined cycle figure of 44.8mpg. CO2 emissions are also remarkably low at just 148g/km. The 3.5-litre DOHC petrol engine is based on that used in the RX 350, but has been adapted specifically for use in the hybrid powertrain. It produces a maximum 246bhp (249 DIN hp) at 6,000rpm and 317Nm of torque at 4,800rpm, and features three Lexus hybrid 'firsts' to optimise the fuel efficiency: Atkinson Cycle, Cooled Exhaust Gas Recirculation (EGR) and Exhaust Heat Recovery (EHR).

The hybrid drive system benefits from refinements in drivability through expanded electric motor maximum torque bands and a new AI-SHIFT transmission control strategy to optimise engine efficiency.

Three new driving modes, ECO, EV and SNOW, further improve the system's fuel efficiency and driving performance. EV mode, available only with the full hybrid capability of Lexus Hybrid Drive and not available to drivers of mild hybrid vehicles, allows the car to be driven under electric power alone, with minimal noise and zero CO2 and NOx exhaust emissions.

Driving Dynamics

The new RX 450h was designed specifically to meet the dynamic handling requirements of the European market and sets new standards for handling and driving enjoyment in the SUV segment. It delivers the high-speed cruising comfort and composure of a premium saloon, responsive handling and agility on winding roads and, through its electric four-wheel drive system, stable and tenacious performance.

A new double wishbone rear suspension configuration replaces the strut-type system used in the RX 400h. Allied to an increase in wheelbase length and track width, this enhances body roll and pitch control. The front suspension has also been extensively re-engineered, with new shock absorbers, optimised springs, anti-roll bar and component geometry.

Dynamic ability is further improved by an active stabiliser system, reducing body roll by almost 40 per cent in 0.5G corners. 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.

Design

The new RX 450h combines the road presence of a premium SUV with the most compact packaging possible. It is 15mm longer, 40mm wider, 10mm higher and has a wheelbase that is 25mm longer than its predecessor, but these increases have been kept to a minimum in order to preserve the car's agility and town-friendly manoeuvrability. RX maintains its class-leading 5.7m turning circle. The reduction of panel gaps and the management of airflow under the vehicle combine with several multi-function aerodynamic elements to minimise turbulence and give the RX 450h a class leading drag coefficient (Cd) of 0.32.