Junichi Furuyama, Chief Engineer Lexus IS range.

Lexus is hoping its new crop of IS models will help it to break out of its ‘conservative’ mould. Paul Murrell talks to the man responsible for making the new Lexus IS “fun to drive”.

Practical Motoring: The new Lexus IS looks very dramatic. What influenced your design decisions?

Furuyama: “I really like the way it looks. The style is sportier and more athletic. To my eyes it cuts a confident, more dynamic figure. It’s also very aerodynamic, with a low 0.27 Cd rating.

“There is more emphasis on the car’s individuality than before. Take the headlights: the daytime running lights, where fitted, use L-shaped LEDs that are constantly illuminated when you’re driving. They tell you instantly that this is the new IS. It’s clearly a premium car, but obviously a sporting one.”

Practical Motoring: There are clear influences from the LFA super car and the LF-CC concept car…

Furuyama: “The new IS expresses the direction Lexus is taking as we evolve L-finesse. We’ll continue to make our cars look more distinctive. It is a continuation of the Lexus F concept, which culminated in the LFA. The F-Sport captures the visual drama of the high-performance IS F, with exclusive front and rear spoilers and bespoke 18-inch wheels.

“As for the interior, it shares characteristics with the LFA such as the horizontal instrument panel. The centre control pad flows forward into the centre of the dashboard. From the centre of the instrument panel the horizontal movement continues to wrap around to the door armrests. Everything flows horizontally. The areas for the control pad and centre display are both clearly distinguished. You navigate the system using the control pad and the centre display – everything is right in front of you. These are some of the key things we strived for with the interior.”

Practical Motoring: You talk often about the fun factor. How do you define “fun to drive”? And how did you achieve it?

Furuyama: “While the LFA was being developed, we spent long hours test-driving on German and Japanese speed circuits. From there, we were able to collect information and gain insights on what it takes to make a car safe and fun to drive, the kind of things we wanted to do with the IS.

“The development team had to understand the meaning of “fun to drive”. It is very difficult to explain but when we drove cars that were fun to drive versus cars that weren’t, the differences were obvious. We decided we needed to truly understand these differences and put our cars against competitive cars on our Higashifuji test track. At each corner we analysed steering feel, brake feel and speed sensation, comparing our cars to the rival cars. Overall, ours was not as much fun to drive. Systematically, we broke down each corner by varying our driver techniques. For example, taking a certain corner at a certain speed was categorised as “fun”. By doing so, we began to standardise the definition of “fun to drive”.

“The development of the new IS began as the Lexus brand was shifting towards a more emotional image. Positioned within the Lexus line-up as a sporty entry sedan, the new IS required outstanding driving performance and styling. There’s nothing more enjoyable than a vehicle that responds to the driver’s intentions while you are driving. The vehicle starts to turn as soon as you turn the steering wheel. As you accelerate rapidly, the vehicle follows your intended line. Actually, the vehicle responds slightly better than the driver expects – this will surely turn enjoyment into delight. Less responsive vehicles don’t turn straight away when you turn the steering wheel. You turn the wheel farther because you think you haven’t turned it enough. Then when the vehicle starts to turn, you end up rapidly trying to turn the wheel back again. This means you need to continually pay careful attention as you drive. You can’t really enjoy driving a vehicle like that, can you? As the wheels turn, you can feel it through the steering wheel. As a result, the vehicle turns only as much as the driver wants to turn. You can feel this not just when driving at high speed, but even as you start off during normal everyday driving. That’s what makes the new IS fun to drive.

“As for performance, the engine and transmission are the same in the standard IS and IS F-Sport editions. For the IS350 F-Sport, we did additional sports tuning to the suspension, adding Sport S+ mode as a fourth setting to the Drive Mode Select. When you turn the dial to Sport S+ mode, the adaptive variable suspension can give the feel of a sports car.”

Practical Motoring: How did you change the way you went about the development of the IS?

Furuyama: “We took a radically different approach. Normally we would aim to thoroughly develop and refine each aspect of basic performance. The idea is to start with a firm base and build up from there like a pyramid. That was the idea but unfortunately, we found that proceeding in this way would not necessarily result in a fun-to-drive vehicle.

“This time we decided to start by focusing on creating a fun vehicle as a primary objective. Of course, for a vehicle there are various other aspects of performance, but these could be incorporated in the latter stages after we first developed the fun aspects of performance. In doing so, we turned our performance development priorities around completely.

“One of the most effective elements in embracing the performance was the use of body adhesives. However, body adhesive is not easy to make. It required an initial investment. This raised concerns within the company as to whether it was actually necessary to go that far. When we built and tested a prototype, the difference was absolutely clear. We realised we would have to convince all the key people by getting them to actually drive it for themselves, so that’s what we did. Everyone who drove the vehicle, including the president, realised the value of this method and as a result, permission was given. This became a driving force that moved things along significantly within the company.

“At the test course we often use, we brought in an IS and its competitors to compare driving performance. We found that most people more or less agreed on which aspects were fun. We checked on the achievement of these aspects as milestones during development. That’s how we proceeded. Then in the final stages of development, while I was conducting performance checks on a circuit, I felt the new IS to be enticing me to press the accelerator further and further. It felt almost like I was engaged in a dialogue with the vehicle. I had only intended to evaluate the performance by conducting the usual checks, but before I knew it, I was going all out and working up a sweat. I was totally absorbed in driving the vehicle. That was the moment when I realised we had actually succeeded in producing the vehicle we had envisioned. I felt this vehicle may be capable of surpassing the competitors and furthermore, achieving significant breakthroughs.”

Practical Motoring: You have been able to make only minimal improvements to the engines. Why were they not upgraded at the same time?

Furuyama: “Being Chief Engineer is similar to being a director or producer in film making. There are budgets, constraints and logistics to consider. Sometimes you cannot create one 100% of what you envisioned but you make every effort to reach as close to one 100% as possible.

“As soon as I was assigned to be the IS Chief Engineer, I drove all the rival cars and studied the differences. Unfortunately, while I thought the IS was one of the sportier and more enjoyable cars in this segment, I found out that the BMW 3 Series and Mercedes Benz C-Class were actually a few steps ahead of us. That was my initial feeling.

“Even before I was appointed Chief Engineer on the IS project, my daily driver was an IS. I started developing this car to leave its mark in history. We’re trying to change the perception of the Lexus brand. In addition to being reliable and comfortable, we’re looking to be a more emotional and aggressive brand and we’re currently in the midst of that transition. The IS is a vehicle that will move you both physically and emotionally.”