Making its European debut at the 2005 Frankfurt Motor Show, the new Lexus GS 450h luxury sports sedan follows the RX 400h SUV as the second production vehicle to introduce the technical sophistication and high-performance attributes of Lexus hybrid drive engineering to the premium automotive segment.
On sale throughout Europe from the spring of 2006, the new GS 450h further reinforces the importance of hybrid drive systems as the core powertrain technology for the Lexus luxury marque. Its new hybrid drive-train encapsulates precisely the type of driving characteristics that are the hallmark of Lexus drive-train engineering; smooth, powerful and refined, yet offering a highly engaging and rewarding driving experience.
The Lexus GS 450h is the world`s first hybrid luxury sedan to combine front engine mounting with the rear wheel drive essential to sports driving dynamics.
The latest hybrid petrol/electric powered addition to the luxury Lexus range is named "450" not to indicate the cubic capacity of the engine but, rather, in recognition of a power output comparable to that of a conventional 4.5 litre, V8 petrol engine, whilst the `h` suffix indicates the presence of Lexus` highly sophisticated hybrid drive system.
Displaying similar operational characteristics to the RX 400h`s Hybrid Synergy Drive?? system, a completely new, front engine, rear-wheel drive Lexus hybrid powertrain has been engineered for the GS 450h.
It features an ultra smooth running, 3.5 litre D-4S direct injection V6 petrol engine generating over 210kW/286 DIN hp mated to a high-output, permanent magnet electric motor developing over 140kW/190 DIN hp, driving the rear wheels both independently and in tandem, as appropriate. The system produces a total power output of more than 250kW / 340 DIN hp.
The petrol engine combines a new D-4S fuel injection system with high strength chain drive and roller rockers, and high torsional stiffness connecting rods. New, double slit, fan-shaped spray injectors optimise the fuel/air gas mixture formation for maximum combustion efficiency, generating higher rpm and power output with minimal emissions. The new D-4S system`s combination of direct and port injection realises optimum engine efficiency throughout the power band. Direct injection improves full-power engine performance, whilst both low-power engine fuel economy and emissions reduction are enhanced through the coalition of direct and port injection systems.
In addition to the petrol engine, the new GS 450h Hybrid Synergy Drive?? system comprises a power control unit, a high performance nickel-metal hydride battery and a power transmission unit.
The power transmission unit consists of an electric motor, a generator, a power split device and motor-speed reduction gears. Via planetary reduction gears, the power split device combines and re-allocates power from the engine, electric motor and generator according to operational requirements. As in the RX 400h, these system components are all housed in one lightweight, highly compact transmission casing.
Unique to the GS 450h, however, the new hybrid transmission system now incorporates two-stage motor speed reduction gearing. Through the new luxury sedan`s seamless, continuously variable automatic transmission, the twin stage gearing generates maximum low-gear torque for significantly enhanced acceleration, as well as extended high-gear performance for quiet, high speed cruising with improved fuel efficiency in almost all driving conditions.
Via a centre console mounted switch, the new hybrid transmission also offers a choice of three power settings; "Normal", for the optimum balance of power and traction, "Power", for maximum acceleration, and "Snow", for excellent traction control under the most slippery road conditions. Moreover, with the "Sport" manual gear change mode selected, each of the 6 sequential "steps" in gearing incorporates engine brake force in the manner of a conventional transmission, improving vehicle control and further enhancing the GS 450h`s high performance sports driving experience.
HYBRID SYNERGY DRIVE? IN OPERATION
Over the course of any journey, the new hybrid drive system operates in several different modes to maximise the GS 450h`s overall efficiency: At rest, the engine stops automatically to conserve fuel. Under operating conditions of low engine efficiency such as start up and low to mid-range speeds, the vehicle runs on the electric motor alone, thus eradicating CO2 emissions and providing exceptionally quiet operation. Under normal driving conditions, engine power is divided by the power split device to both drive the wheels directly and power the generator which, in turn, drives the electric motor.
In these circumstances, power allocation is constantly monitored and adjusted between engine and motor to maximise efficiency. When sudden acceleration is required, engine and electric motor again operate in tandem, with extra power supplied from the battery to boost motor response.
During deceleration and under braking, the engine switches off and the electric motor acts as a high-output generator. This regenerative braking system optimises energy management in the new GS 450h`s Hybrid Synergy Drive? system by recovering kinetic energy (normally wasted as heat under braking and deceleration) as electrical energy for storage in the high performance battery. Furthermore, battery power level is constantly managed via the engine driven generator to obviate any requirement to recharge the system from an external source.
The new powertrain equips the Lexus luxury hybrid sedan with performance characteristics on a par with conventional 4.5 litre V8 engined models.
Combined power output is over 250kW / 340 DIN hp, and the new GS 450h will accelerate seamlessly from 0-100kph in less than 6.0 seconds, the Lexus hybrid transmission system eradicating the expected `jumps` between gears of a conventional drive-train.
Equally impressive is the potent mid-range torque afforded by the system`s powerful electric motor.
Operating in tandem with the V6 petrol engine, it is capable of delivering maximum torque instantaneously, and seamlessly, upon demand. This characteristic is most beneficial in mid-range acceleration during overtaking manoeuvres, and the Lexus GS 450h will accelerate from 80 to 120kph in under 5 seconds.
Conversely, the GS 450h also proves substantially more frugal than comparable sports sedans, returning combined fuel economy figures on a par with those of a 4-cylinder 2.0 litre engined vehicle. Moreover, already compliant with EURO IV emissions standards and rated SULEV (Super Ultra Low Emission Vehicle) in the USA, the new Lexus returns CO2 emissions of under 195g/km; markedly less than rival, premium sector sedans with similar engine power.
The new GS 450h is equipped with a class-leading range of active and passive safety systems, including the second generation of Lexus` state-of-the-art Vehicle Dynamics Integrated Management (VDIM) system, to enhance performance, traction control and vehicle stability (For more information about VDIM, please also read section 5: `Lexus Safety Technology`)
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