1. What they worked toward
Yoshihiko Kanamori is the chief engineer at the Lexus Development Center Product Development Group in Japan. He’s worked for Toyota Motor Corp. (TMC) since 1982. During his tenure at TMC, he was in the Body Design Div., working on Celicas and Corollas. He was in Product Planning Div. He went to Advanced Development Div., where he developed a new platform for a C-segment hatchback. He moved to Lexus in early 2007. When he went over there, they were planning the car that was to be the fourth-generation Lexus GS. And he was named chief engineer for the car.
During this development program, several things happened, particularly externally. Like Toyota and Lexus brands being dragged through the headlines. In June 2009, Akio Toyoda, then 53, took over TMC. On a personal level, he is a man who is interested in fast cars and racing. On a professional level, he is a man who faced a tremendous challenge in addressing the issues that faced the company that his grandfather had founded.
So for the GS development program, Kanamori recalls, “Akio Toyoda set a high level.” To meet that level, they established a team that, Kanamori says, went beyond the genchi genbutsu—“go and see”—characteristic of Toyota Production System programs. They traveled around the world—from China to Chile, from the U.S. to Hungary—talking to people who owned GSes or the competitive vehicles, testing under various conditions, driving relentlessly, determining what it would truly take to, as he put it, “move to the heart of the midlux market,” to the place where the Mercedes E Class, BMW 5 Series, and Audi S6 are already well established.
As a result of the research and the consequent development work, Kanamori is convinced that the fourth-generation GS “will change the way people think about driving a Lexus.” He amplifies: “An emotional driving experience is most important. For an emotional driving experience, I believe a car must provide the agility, acceleration, and braking a driver expects.” Expects whether driving on a challenging road or a highway. “For many drivers, it means both—but with no compromise.”
There were four key objectives that the GS team worked toward achieving:
1. Creating an emotionally intriguing driving experience
2. Developing a new design direction (this is most pronounced in the front end, with a design cue that they’re calling a “spindle grille”—note how there is an hour-glass like tuck in)
3. Advancing the technology of hybrid technology for a front-engine rear-wheel drive car
4. The “smartest packaging in the class” for a four-seat “Grand Touring Sedan”
2. The road to the fourth generation
The first generation GS lasted from 1993 to 1997. There are a couple of notable things about the car that are things that vehicle manufacturers don’t often reveal. One is that the design of the car had participation by Giorgetto Giugiaro of ItalDesign. (Yes, while you might think that vehicle manufacturers would boast about having high-caliber independent designers working on vehicles, there is a tendency to want to make it seem as though everything is internal.). The other is that the Lexus shared drivetrain components with a Toyota. But what a Toyota: the Turbo Supra also used the 3.0-liter, DOHC in-line six (as did the Lexus SC 300 of that period).
The second generation GS ran from 1998 to 2004. This had the development theme “The Pursuit of Speed.” It had a top speed of 155 mph which, at the time, made it such that the company was able to claim it as “the world’s fastest sedan.” Production sedan. The GS 400 shared a 4.0-liter DOHC V8 with the LS 400.
The third generation GS had a production run from 2007 to 2011. Notable about this generation is the fact that it included the GS 450h, a hybrid. The claim here was that it was the “first mass-produced rear-wheel-drive hybrid.” What’s more, while hybrids were more or less considered in the context of being simply fuel-efficient (and often comparatively anemic), here was a 3.5-liter V6 mated to electric motor/generators such that the total output was 339 hp. (The aforementioned “world’s fastest sedan” was rated at 300 hp.) The 0 to 60 time: 5.2 seconds. Top speed: >130 mph. Fuel economy: 22/25 mpg (city/highway). (See: autofieldguide.com/articles/lexus-gs-talking-performance-and-technology)
The fourth generation GS, 2013 to ? Although performance is a key attribute, and while performance has long been associated with the V8, there is no V8. (Lexus vp and general manager Mark Templin: “In this segment, 95% of the cars don’t have a V8.”) The alternative: the GS 450h, the hybrid. In addition to the GS 450h, there are other variants of the car: the GS 350 with F Sport package, the GS 350 with all-wheel-drive, and the GS 350 without F Sport package and with rear-wheel-drive.
3. Engineering improvements
One of the things that the Lexus engineers worked on was developing a vehicle that is light and aerodynamic. So to make the exterior upper body, for example, they made extensive use of high-strength, and ultra high-strength steels, and even a hot-stamped steel for the B-pillar (contributing to safety). Of the total mass of the upper body, which is 529 lb., 146 lb. are one of these high(er) strength steels. There are also 24 lb. of aluminum alloy. On the underbody, which has a total mass of 375 lb., there are 218 lb. worth of the advanced steels. (No aluminum in that lower structure). So overall, upper and lower body combined, there are a total 40.2% of the advanced steels.
Weight was saved in the interior, too. Materials were modified so that there is an overall 10% weight reduction compared to the previous car. The door trim is 21% lighter; the headliner down 14%; trunk trim reduced 20%; trunk lining 28%; tunnel silencer 10%; carpet 3% and center pillar lower garnish 10%.
The car’s coefficient of drag is a slippery 0.26. That’s down from the 2011 model’s 0.27 Cd. To get it, the engineers added an underbody cover—including under the transmission—and aero stabilizing fins to control turbulence. There is a groove in the finer liners to smooth airflow over the tires. The rear bumper lower section angle is set at 25°, which directs the underbody airflow toward the rear of the vehicle. There are spats in front of the rear tires. The trunk edge has a sharp line to direct the airflow from the roof (there is a rear spoiler on the F Sport model).
4. Structurally sound
To make the car drive and handle well, considerable effort was made to the body structure. According to Paul Williamsen, national manager, Lexus College, there was extensive use of computer-aided engineering (CAE) deployed to analyze body distortion during simulated driving so that they were able to determine the specific areas on the car where they would need to add reinforcements to enhance the body rigidity.
For example, there is a high-strength steel cowl side brace deployed to increase the rigidity of the front suspension and steering mounts. There is an A-pillar-to-apron member brace. There is the aforementioned hot-stamped B-pillar frame member.
But there are other measures included utilizing laser welding, particularly in high-stress areas of the structure (e.g., corner seams; in the underbody where the rear suspension is attached). Also, there is an increase in the number of spot welds used. Williamsen notes that not only was there a numeric increase, but there was a “microanalysis of where the spots were positioned” so that along a given seam there are areas where the spots are more or less numerous (i.e., there is not a consistent spot/spot/spot but perhaps spot/space/spot/spot/spot).