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Interior design, millimeter-perfect precision

"99% of time with your car is spent on the inside”
People talking about “car design”, most probably think of exteriors – the sleek form of a coupe or an angular, rugged SUV. Toyota designers, with a burning passion for car interiors, insist that right now it’s all about interior design.

Trying not to chip those nice nails

“In a car interior, changing things by a mere millimeter can throw everything off. It’s a delicate, complex world,” says Hiromi Yagi, Assistant Manager at the Lexus Design Division. He also worked in exterior design before shifting to interiors.

For interior designers, the “mere millimeter” is by far an exaggeration. By using fake fingernails for example, when evaluating their design, they can easily understand how the change by a millimetre might affect the operation of an in-car dial.

Of course, we use fake nails to make sure controls are easy to operate, but more importantly, we put ourselves in the shoes of the woman who cares about her nails. When you look at it from the perspective of not wanting to damage those nice nails, you understand what angle a dial needs to be, which doesn’t come across in size simulations alone.
Hiromi Yagi, Assistant Manager Lexus Design Division

Knee braces and special glasses

Sometimes, designers walk around with a weighted brace on their knee. These braces add weight or immobilize the joints, allowing them to make sure that even the elderly and physically challenged can get in and out of the car smoothly.

They also have special glasses to check if the red hazard switches are easily visible for those with difficulties seeing red hues. All user needs are considered, seeking to balance stylish looks with usability for many different customers.

Embracing global diversity and considering the needs of many different people, embodies the “human-centred” approach to car-making at Toyota and Lexus.

Why “simple is best” for the Lexus RZ interior

For the interior of the RZ, Lexus' first BEV-only model, the designers decided that simple is best. Since BEVs are not equipped with an engine, the interior has more room from front to back.

Conventional interior design treats the driver-side instrument panel as the main feature. However, for the new RZ, designers aimed for a new spatial configuration focusing on the doors.

From the sketch stage, the aim was to accentuate the elongated interior space. The resulting interior is open and uncluttered. Meticulously crafted elements such as the steering wheel and gauges offer a sense of detailed, refined monozukuri (manufacturing).

What’s with the animal bone look?

This bone-like structure is a car seat frame created using a design method known as generative design, which has attracted much attention in recent years, explained Project Manager Shinsuke Omori of the Vision Design Division’s Interior Design Department. Parameters such as the size of the space, the weight of the seated person, and forces during impact go into the software, then 3D-print the generated design. By taking full advantage of the latest tools, designers have opened up possibilities for creating entirely new seat designs.

Different tools, different ideas

Another interesting finding is that results optimized by the most advanced digital tools come to resemble the skeletons of animals that have inhabited the earth since time immemorial.

“Depending on the tools you use, different ideas emerge,” adds Omori.

A core principle of the Toyota Production System is “continuous improvement,” and the company’s designers strive for ever-better designs by constantly adopting the latest tools.

Virtual reality headsets

Our designers also use virtual reality headsets to see what a car interior would look like from the driver’s seat. This technology allows to explore the design in great detail from an early stage.

Advances in digital technology eliminate inefficiencies during development. This virtual reality testing is a good example of how new digital technologies can make the work for designers easier.

Interiors have progressed remarkably over the past five years. To create an interior design is to create a living space. It is a quest for human comfort. The shift from cars to mobility expands these possibilities still further.

While exterior design is mostly about exploring form, interiors are interesting because you can be involved in every aspect of design. You can design parts such as the instrument panel and steering wheel, down to the materials they’re made from. Or, by playing around with things like switch usability, the clarity of driving information, and the layout of people and objects, you can create comfortable interior spaces like nothing that has come before.
Shinsuke Omori, Project Manager Vision Design Division