Having recently gone on sale in markets throughout Asia, the Pacific Rim and North America, the fourth generation Lexus GS will soon reach dealers in Europe and Russia. Yoshihiko Kanamori, the car’s chief engineer, spoke to just-auto at a media preview drive event in Austria and Germany.
Glenn Brooks: Driving the GS 450h both on the autobahn and in the alps this afternoon it’s clear that this is a car that feels at home in Europe. What changes did you make over the GS sold in, say, Japan or the US?
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Yoshihiko Kanamori: Do you mean suspension settings?
GB: Yes.
YK: Globally, it’s the same. One standard.
GB: Even though the US will be the car’s main market?
YK: We developed the car to European standards because the conditions here are so tough on vehicles. The development work was done mainly in Europe, though extreme hot and cold weather testing took place in other places.
GB: What TMC (Toyota Motor Corporation) platform is used for the new GS?
YK: This is the N-platform. We use alphabetical names for our platforms. This GS platform is completely new. Maybe another Lexus will use the same platform, but now it is only for the GS.
GB: That means other rear- and all-wheel drive cars – the replacements for the LS and IS?
YK: LS is on the L-platform. I cannot comment on the IS replacement as I am not the chief engineer for that car (he grins).
GB: So a new platform, even though the wheelbase is identical to that of the old GS and the car’s other dimensions are also similar.
YK: It is a brand new platform. We did not change the wheelbase as the most important thing with the GS is handing. If we stretch the wheelbase, agility is reduced. I decided that it is better to keep the same wheelbase.
GB: And is there a cost saving for manufacturing?
YK: (He answers through the translator for the first time). Yes of course there were benefits for CapEx by keeping the same wheelbase measurement but we also had a look at the amount of rear seat space that we wanted. If we increased the wheelbase, that meant we might jeopardise the handling, so we couldn’t do that.
GB: The new car line-up consists of the GS 250, GS 350 and GS 450h: each powered by a V6. Why is there no replacement for the GS 460?
YK: (He smiles) I know journalists love V8 engines! Two months ago I went to Sydney for the Australian test drive launch in the Blue Mountains. There, each journalist asked me the same question! (he laughs).
So, the answer is that we are environmentally conscious and we wanted a hybrid as the top model. And so, we took the decision not to replace the V8. Also, the take up volume for the former GS 460 was very small. So, the new GS 450h is not only the most powerful car in the range, but its fuel efficiency and emissions make it more appealing for those customers who want the power of a V8 but they have the advantages of the hybrid powertrain.
GB: The Infiniti M offers not only a petrol hybrid but also a diesel in European markets. And now Mercedes-Benz has a diesel-hybrid E-Class. When should we expect a GS diesel or diesel hybrid?
YK: This time we didn’t develop a diesel or diesel hybrid. Diesel engines are expensive (to develop).
GB: And yet the majority of cars in the European E-premium segment are powered by four-cylinder diesel engines.
YK: We can’t use a four-cylinder engine easily in the GS and anyway, for NVH, a four-cylinder diesel is not ideal. And so what we offer our customers is a range of V6 petrol engines, with the hybrid as the top engine.
GB: I noticed when looking at the car earlier that the boot space is far larger in the GS 450h than it was in the old car. What engineering changes did you make to achieve this – did you somehow shrink or repackage the hybrid components?
YK: Yes, the space behind the rear seat now has a differently shaped hybrid battery, so we have more room for the boot, and the auxiliary battery is now under the floor.
GB: And obviously you must have worked closely with the battery supplier to specify this new, stacked configuration for the hybrid system’s cells.
YK: Yes, I used the same supplier as previously, Panasonic, and also, the battery capacity is the same as previously. But the battery had to be repositioned, or restacked.
GB: What is your priority for future hybrid system batteries: lower weight or more compact designs?
YK: Both! Toyota and Lexus specify the battery design and we must work with Panasonic for the ‘world standard’ specification.
GB: What are your thoughts on the quest to remove weight from cars – after all, the new GS 450h weighs almost 2,000kg if you include the driver?
YK: The new GS hybrid is lighter than the previous model. We have changed the materials in some parts – when we redesigned the rear suspension for better handling and more boot space we also made the components lighter. We have used more high tensile steel too. And previously we used asphalt sheets for sound deadening, now we have a spray-type material. The advantage is that we use less in places where it does not need to be so thickly applied.
It is very important that you do not remove the refinement of a luxury vehicle when you seek to take away weight. On a Lexus you must not compromise the luxury aspects just for the sake of making a lighter car: this would be unacceptable.
GB: What project will you move on to next?
YK: No, I am not leaving the GS. I will stay as chief engineer because I must specify and evaluate the next model year changes. If there is a specification change, maybe the performance of one engine, then I am responsible for that. My job continues.
GB: That suggests there will be another engine to come for the GS.
YK: Yes, we have a lower displacement hybrid. It will come to European markets in the second half of 2013.
GB: When will you be shifted to another, future model?
YK: I don’t know; that is for my boss to say.
GB: Is it likely that as a chief engineer for a Lexus model that you would stay with Lexus or might you be assigned to a future Toyota vehicle?
YK: Maybe. (He then considers the question further) With Lexus. Yes, it is likely. Toyota and Lexus Group are different. If people who are working for Lexus keep going back to Toyota, I think it defeats the objective of trying to build on the brand’s exclusivity. So people who are working for Lexus generally will stay.
GB: What are your thoughts on Lexus entering new segments. For example, rivals for the Audi Q5 and Q3?
YK: Hmmm….maybe (he laughs). I cannot say. But maybe. Yes, we have the CT, and sedans – ES, IS, GS & LS and SUVS – GX, RX and LX but not compact SUVs.
GB: What about some more coupes to fill the gaps compared to your rivals?
YK: There is the IS-C but yes, I think maybe it would be good to have a ‘star’ for each segment as Audi does – more coupes would be good.
GB: And what happens after the 500th LFA is made in December? Will there be another production run, perhaps a convertible version?
YK: An LFA spyder? I cannot say, I am sorry (but he smiles).
