Toyota Revamps Lexus GS, Improves Fuel Efficiency of HEV Model

Jan 31, 2012
Naoshige Shimizu, Nikkei Automotive Technology
The front grille of the "GS350" contains a trapezoidal shape. Toyota calls it "Spindle Grille" and plans to use it for future models in the Lexus series.
The front grille of the "GS350" contains a trapezoidal shape. Toyota calls it "Spindle Grille" and plans to use it for future models in the Lexus series.
[Click to enlarge image]
The hybrid system of the "GS450h"
The hybrid system of the "GS450h"
[Click to enlarge image]

Toyota Motor Corp announced Jan 26, 2012, that it has fully remodeled the "Lexus GS" sedan.

All gasoline-engine models of the new Lexus GS come with a V-6 engine. And Toyota released the gasoline-engine "GS350" (displacement: 3.5L) and "GS250" (displacement: 2.5L) Jan 26, 2012, and will release the "GS450h" hybrid electric vehicle (HEV) in March 19, 2012.

The price of the new Lexus GS starts from ¥5.1 million (approx US$66,815). Toyota aims to sell 5,000 units per month in the global market (more than 2,500 in North America and 600 in Japan). The new GS is manufactured at the Tahara Plant in Tahara City, Aichi Prefecture, Japan.

Engine
The GS450h HEV features a fuel efficiency about 40% higher than that of the former model. It is 18.2km/L (approx 42.8mpg) under the JC08 test mode and 20.5km/L (approx 48.2mpg) under Japan's 10-15 mode test cycle. It is equipped with the "D-4S" system, which uses the "2GR-FXE" 3.5L engine and is capable of both direct fuel injection and port injection.

The D-4S was developed based on a system that Toyota developed in 2005. This time, the company improved the injection pressure of an injector for direct injection, reduced the diameter of its nozzle and changed the shape of injected fuel from a two-forked shape to the shape of a fan. As a result, air and fuel can be mixed well, making it easy to combust fuel.

In addition to the use of direct fuel injection, the shape of the combustion chamber and the cooling system were improved so that the generation of knocking can be prevented and compression ratio can be improved from 11.8 to 13.0.

Furthermore, Toyota employed the Atkinson cycle, which closes the inlet valve at a later timing to improve the heat efficiency of the engine. The maximum heat efficiency in the operating range is about 38%, which is 2% higher than that of the former model. The maximum output and maximum torque of the engine are 217kW/6,000rpm and 356N·m/4,500rpm, respectively.

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