Lexus GS 450h
From Lexus press: The GS 450h hybrid luxury sport sedan enters the 2010 model year with stylish exterior changes. Several exclusive design features, including grille, clear taillamp covers and 18-inch alloy wheels, were updated for 2010 and add to the existing advanced technology, high performance and indulgent luxury of the rear-wheel-drive GS 450h. Unique, blue hybrid badging is shared across the Lexus hybrid line-up and also distinguishes the GS 450h from the gas-powered GS 460 and GS 350.
Based on the GS platform and featuring Lexus Hybrid Drive technology, the GS 450h offers V8-like performance with greater fuel efficiency. In addition to boosting performance and fuel efficiency while lowering emissions, Lexus Hybrid Drive technology also further accentuates the brand's renowned smooth, quiet operation.
A full hybrid, the GS 450h is capable of operating in gas-only or electric-only modes, or a combination of the two. With its unique transmission, the GS 450h was the first hybrid vehicle to enable the electric drive motor to contribute to highway performance, not just slow-speed driving.
The GS 450h model’s version of the Lexus Hybrid Drive powertrain combines a powerful 3.5-liter V6 engine with a compact, permanent magnet electric motor – all driving the rear wheels. The hybrid powertrain collectively produces 340 horsepower and can effortlessly accelerate the GS 450h from zero-to-60 mph in just 5.2 seconds.
Just as impressive as the GS 450h's acceleration from a stop is how quickly and powerfully torque is delivered during mid-range acceleration. The hybrid system's electric-drive motor delivers maximum torque immediately upon demand. This unique power-delivery characteristic is most noticeable, and most useful, during 30-to-50 mph passing and in traffic-merging maneuvers. The GS 450h returns EPA-estimated fuel economy of 22 mpg city/25 highway/23 combined and is certified as a Super-Low Emissions Vehicle II (SULEV II).
One of a new generation of Lexus engines, the gasoline V6 uses an Electronic Throttle Control System with intelligence (ETCS-i) and a dual fuel-injection system that combines the benefits of direct injection with those of port injection. Dual Variable Valve Timing with intelligence (VVT-i) operates on the intake and exhaust valves to further enhance power and torque across a broad engine speed range.
The GS 450h hybrid powertrain uses two motor-generators, MG1 and MG2 (the drive motor). Each performs specific functions and can operate as both a motor and a generator, although MG1 is used as a starter motor and provides no motive force. The engine-driven generator (MG1) can charge the battery pack or provide additional power to MG2 as needed.
A 288-volt DC Nickel Metal Hydride (Ni-MH) battery pack is installed behind the rear seat area. The battery's power is directed through a “boost converter” that can efficiently raise voltage to a maximum 650V DC. An inverter changes this to AC, providing its elevated power to the 147-kW electric motor, which turns as high as 14,400 rpm. A 12-volt auxiliary battery powers various vehicle systems, including audio and navigation.
Power from the gas engine and MG2 is distributed to the rear drive wheels via a planetary gear-type Electronically-controlled Continuously Variable Transmission (ECVT). This special transmission, which eliminates specific gear ratios, features a two-speed torque-multiplication device that allows drivers to select from among three driving modes: Power, Normal and Snow. “Normal” provides the smoothest operation and is ideal for city or suburban driving; “Power” sharpens accelerator pedal response, and “Snow” mode softens accelerator pedal response making it easier to travel on slippery road surfaces.
The ECVT consists of a motor generator, motive power-dividing mechanism, two-stage motor-reduction device, electrically powered oil pump and hydraulic control system. The two-stage torque-multiplication device varies the gear ratio in two stages by controlling a planetary gear and two wet brakes, similar to the way a conventional automatic transmission operates.
This configuration allows the electric drive motor to operate in high or low ranges, with seamless transitions between the two. MG2 can therefore contribute power not just for acceleration, but at higher cruising speeds as well.
The GS 450h is driven solely by its electric motor when starting, traveling slowly, and during low-load driving, the resulting super-quiet operation enhancing the luxury experience. A regenerative braking system further boosts system efficiency. When the vehicle is coasting or the brakes are applied, the electric motors function as generators, capturing kinetic energy that would normally be lost as heat through the brakes and transforming it into useable electricity to recharge the batteries.