Exclusive Interview with Lexus CT 200h Chief Engineer

Lexus CT 200h Chief Engineer Osamu Sadakata

Although I wasn’t able to attend the Geneva auto show and see the Lexus CT 200h debut in person, I did get a very special chance to virtually interview the two men central to the creation of Lexus’ new hatchback model.

By way of the good folks at Lexus Europe, I sent questions by email to both Chief Engineer Osamu Sadakata & Chief Designer Takeshi Tanabe, who in turn provided very detailed answers. I’ve broken up the interviews into two parts—let’s start with the Q&A with Sadakata-sama:

TLE: Is the CT 200h built on an entirely new platform?

Sadakata: The new Lexus CT 200h, is built on a new platform with a unique suspension set-up, specially developed with European customer’s requirements in mind, offering them a dynamic driving experience.

TLE: Why start with the Prius 1.8L instead of something like the HS 2.4L engine?

The new Lexus CT 200h has been developed with Europe in mind. In Europe, lower displacement engines with better fuel efficiency are favoured by customers and the vast majority of vehicles sold have engines with a displacement of less than 2 litres. However, despite using lower displacement engines, European premium compact vehicles deliver superior driving dynamics and good fuel efficiency.  With the 1.8l full hybrid powertrain of the new Lexus CT 200h, we expect the car to be positioned at the heart of the premium compact segment, offering a dynamic driving experience, and class leading emissions (CO2, NOx, and particulates).

TLE: Will additional powertrains be offered?

Sadakata: We cannot comment on possible future powertrains.

TLE: How does the electric motor response change when the Sport Mode is engaged?

Sadakata: The new Lexus CT 200h is unique in having the ability to offer two totally different ‘on-demand’ driving moods. When Sport Mode is selected engine revs are held higher. The PCU (Power Control Unit) that controls the hybrid system boosts supplied voltage by 150volts to a maximum of 650 volts, increasing overall powertrain output.  Sport Mode also provides more linear Electric Power Steering (EPS). Vehicle Stability Control (VSC) and traction control are less intrusive allowing for more lively driving.

In Relaxing mood, drivers will enjoy a much more relaxing and eco-conscious driving experience with specific focus on fuel efficiency and NVH. When ECO Mode is selected, it adjusts air conditioning settings and the throttle for the best possible fuel economy, and the PCU limits system supplied voltage to a maximum of 500 volts. At the same time, driving characteristics change simultaneously.  Milder acceleration feel and driving/EPS controls offer ample assistance to the driver.

Considering the sport emphasis with the CT, why the lack of paddle-shifters?

Sadakata: Paddle shifters were shown on the LF-Ch concept, but in Europe our production vehicle philosophy has changed slightly. We have decided to focus on the on-demand sport driving mode. 

Conventional PCU’s allow only one type of maximum drive power voltage.  In a Lexus first, a new drive power switch mechanism has been added to create a mode select system to provide a unique dynamic driving experience. The function of this new drive power switch was described in the CE’s previous answer on how the petrol engine and PCU respond in Sport and Eco Mode.

Will we see the CT 200h using li-ion batteries in the future?

Sadakata: Toyota Motor Corporation is evaluating and developing a number of different battery technology solutions; however, at this stage we believe NiMh best meets the needs of the automotive market, particularly from a reliability and durability perspective.

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I would like to thank Osamu Sadakata for taking time to answer my questions, and also to Robert Tickner for arranging this opportunity.

Check back tomorrow for a Q&A with CT 200h Chief Designer Takeshi Tanabe!

About Osamu Sadakata

Osamu (Sam) Sadakata was born on March 1st 1958. In 1983, he received an MA in Precision Engineering from the Shizuoka University Graduate School of Science and Engineering, and joined the Toyota Motor Corporation the same year.

Promoted to Project Manager in charge of RX development in 1997 and Project General Manager in charge of the RX 400h in 2002, Sadakata became Chief Engineer of the RX 400h project in 2003. Since then, he has also been responsible for both the LS 600h and the new CT 200h.

This makes him the only Chief Engineer to have led three separate Lexus hybrid vehicle projects, giving him a uniquely extensive breadth of experience in this highly significant field of automotive development.


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