Kazuaki Shingo’s background is in mechanical engineering and internal combustion engines—making him a perfect candidate to develop the world’s most popular electrified car! The Assistant Chief Engineer of the 2016 (fourth generation) Prius chuckles when he tells you that, recalling his seven years spent in control-systems design after joining Toyota as a university graduate in 1996. Shingo-san then got his wish to enter product planning, with subsequent moves back into development of the second-generation Prius hatchback, and the Auris and Prius V programs. He spoke with Automotive Engineering through an interpreter at the 2016 Prius North American media launch.
Were you excited when the fourth-generation Prius was chosen to be the first vehicle developed on TNGA—Toyota’s new global architecture?
Yes! A lot of new Toyota technologies are incorporated into the latest Prius. The new platform raised the bar way up high for us who were developing the car. In fact, in the beginning I was working on both the new platform and the car. We felt this was a great chance for us really capitalize on the new structure to make the car better. And that’s what happened.
What challenges did moving to the all-new TNGA present to your development team, and what benefits did TNGA provide?
There were many challenges. For most of the components we started from scratch. Then it was difficult for team members to integrate the many, many requests for the platform from other departments and projects! But the new global platform created a ‘volume effect’ that make the vehicle prices more affordable. And it gives us more freedom to engineer different variants.
Also, at the time we were creating the new platform, we faced a number of challenges that came one after the other: first the ‘Lehman Bros. shock’ then we had a big earthquake in Japan and also Toyota had some quality-related problems. Not only that, the global market was shifting from the developed countries to the developing countries. I felt the crisis was so significant that our company might not be able to keep afloat. So the company decided to ‘go back to basics’ and create something affordable and with high quality. It was a company-wide decision to focus our efforts on that idea. In order to do that, intra-divisional walls were eliminated. Everybody got together and collaborated. We knew we had something that Japan is very proud of: the ability to manufacture products with very high quality. That spirit enabled us to move forward through the challenges.
In developing the new Prius, what were the 3 main customer desires for the new model?
Prius is Toyota’s ‘hybrid DNA’ so we wanted to maintain the world’s best fuel economy. That was number one. Second, while the previous model’s fuel economy is very good, we also knew that road noise, ride comfort and handling weren’t as good. On a long trip the fatigue level was not so good, and the handling needed improvement. So we wanted to rectify those areas. We wanted the new Prius to be a fun car to drive. And third was the interior aspects—some voices we heard said the old interior was too ‘plasticky.’ So based on those voices we revisited the interior and spent a lot of time on the seats, their texture and design.
Was there an aim to reduce the weight of the new Prius compared with the previous one? You did say the lithium-ion batteries contribute to less weight.
Mass reduction was one of the greatest challenges we had in this development because the fuel economy is very important to us. Making sure the vehicle stays light was one of our most important aims. In addition to that, U.S. collision safety and fuel economy regulations were becoming very stringent; we had to cope with higher collision speeds. Also, to improve ride and handling we decided to install a double-wishbone rear suspension which caused us to raise body rigidity to a higher level. These and other things resulted in an increase in vehicle mass so to compensate we used more aluminum components and high-tensile steel. In the end we achieved a weight level comparable to the older Prius.
The white body is all steel with aluminum hood and liftgate. Was there ever a plan to make Prius aluminum intensive?
Yes, we gave consideration to use of aluminum in more areas. Because this vehicle was going to be produced using the TNGA, that meant it had to be designed for production anywhere in the world. It was a business decision that we had to protect. Also, obtaining aluminum for processing is easy in the U.S. and Japan, but not so easy in developing countries.
What is your greatest achievement on the fourth-gen Prius?
I’m most proud of developing the new hybrid system and also its new platform built from scratch. It’s one way to show the world Toyota’s capability.