Cadillac has revealed what it says is its ultimate design expression of a coach-built luxury electric convertible. The Sollei concept vehicle represents the General Motors luxury brand’s vision of offering modern design in an open-air format inspired by iconic Cadillacs from the past, and it is designed to push the boundaries for future “bespoke” commissions of its intended upper-crust clientele.

The Sollei was revealed at the newly restored Cadillac House at Vanderbilt on GM’s Global Technical Center campus in Warren, MI, which is dedicated to providing a custom design experience for Celestiq clients. Celebrating Cadillac’s heritage of bold colors, the concept’s exterior is hand-painted by craftsmen in Manila Cream, a color originally used on Cadillacs in 1957 and 1958.

“This imaginative design exercise pushes the boundaries of future bespoke commissions, reinforcing Cadillac’s vision of modern design and customization for client desires,” Bryan Nesbitt, Executive Director, Global Cadillac Design at General Motors, wrote on LinkedIn. “Sollei is an illustration to continue our mission to deliver personalization and tailored craftsmanship. As we continue to set the tone for our design future, we look forward to exploring more commissioned design expressions that are unmistakably Cadillac.”

The car’s name is derived from sun (Sol) and leisure (lei), with a launch-event display telling the story of the concept’s inspiration for an open air, leisurely lifestyle, complete with bespoke accessories of a glassware set, 3D printed bird calls, hand-printed silk scarves, and an illustrated journal. Highlights of the all-electric, 2+2 convertible are exterior lighting choreography for arrival and departure and an interior equipped with the brand’s 55-in pillar-to-pillar screen and front and rear command consoles.

“Sollei reimagines the discovery of travel, envisioning a personalized driving experience that connects one with the natural world around them,” said Erin Crossley, Design Director at Cadillac. “The concept celebrates Cadillac’s pedigree of elegant convertibles in a modern form by cultivating high luxury through design expressions and experiences.”

Key contributors were Takahiko Suginoshita for the exterior design and Keunhyuk Choi for the interior design. The car’s low, elongated body is accentuated by a wide stance and long coupe door to ease access to the rear seats. The smooth surfaces and stretched A-line are meant to emphasize the vehicle’s length and the low tail its elegant proportions. Conventional door handles are replaced with buttons for a clean side profile.

 

“Art of travel” interior

The interior is meant to channel Cadillac’s “art of travel” design philosophy and craftsmanship is a key focus of the design. The interior features unstained wood veneers to “honor” their natural colors and grain pattern variations with open pore finishes, with each piece hand-cut and hand-laid using marquetry techniques. The windshield is framed in milled brushed aluminum. The ambient lighting can be customized using 126 color options in each zone for specific moods.

Sollei caters to bird-watching enthusiasts with interior accessories like a brushed metal and leather-wrapped case housing 3D printed acrylic bird calls, a leather-bound journal with hand-painted bird illustrations, and a leather tool roll for pens and pencils made to custom match the vehicle interior. Other highlights are a fully integrated beverage chiller with a power glass door and crystal glasses.

Sun-themed interior details include sunburst-themed lighting, graphic choreography, and sunburst motif perforation, quilting, and embroidery on seats. Keeping the whole interior very light is the Daybreak convertible metallic roof fabric and Bask textured floormat boucle fabric matching the color of the roof material.

The Fine Nappa leather features a pink iridescent pigment that creates a color-changing sunrise effect. A pink iridescent hue on the beverage chiller door and glass tray in the rear compartment reveals different sunlight exposures. An Aurora tint on primary metal finishes includes color shifting to reflect the phenomenon of the sun’s solar winds reacting with the earth’s atmosphere.

 

First application of Fine Mycelium

The Sollei is Cadillac’s first concept vehicle to incorporate a bio-based material developed with MycoWorks, a design leader of premium materials made from mycelium—the renewable root structure of mushrooms—on par with calfskin called Fine Mycelium. Co-founded in 2013 by Principal Philip Ross and Chief of Culture Sophia Wang, the biotechnology company initially launched with luxury fashion applications and counts luxury goods makers Hermes and Ligne Roset as customer partners.

In 2022, the company started a strategic partnership with GM to develop Fine Mycelium technology for the automotive industry, and the Sollei is a demonstration of what’s possible, according to Wang. Futurride spoke exclusively to her and Hannah Dunbar, Industrial Designer, Cadillac and the CMF designer for Sollei responsible for all the colors, materials, and finishes on the interior and exterior of the vehicle, on the novel applications of the sustainable material on the concept.

The material is meant to usher in a new era of luxury materials grown from the renewable root structure of mushrooms and is intended to reflect Cadillac’s mission to pioneer renewable automotive resources. It is used on the concept’s console charging mats, door map pockets, and custom accessories—and has an iridescent finish.

“The Fine Mycelium material is a pure example and exploration of revolutionary resources and collaborations that contribute to an innovative design future,” said Dunbar. “Working with the material and learning about its unique properties, will help to create beautiful texture options impacting future automotive interior applications.”

Fine Mycelium has one of the strongest iridescent effects of any of the materials, according to Dunbar. GM worked with MycoWorks to hone the final color, a cream/off-white that has a yellow-to-pink iridescent effect.

 

Providing sustainable options

According to Dunbar, one of the most important things for the “storytelling” around sustainability is to be able to provide customers with options.

“Working on these really high-end bespoke vehicles, we know that we’ll probably never eliminate a customer’s choice of leather,” she said. “That’s something that is in high demand at this level, but we definitely want to be able to appease the clientele who does want a more sustainable option, something also that’s kind of cutting edge.”

Wang elaborated on giving consumers choices.

“We offer choice without compromise because our fine mycelium offers the elite tactile experience and durability on par with premium leather,” said Wang. “It also aligns with industry-wide shifts towards eco-conscious materials and more sustainable solutions.”

A lot of alternatives to leather right now are really “‘pleathers,’ based on plastic and synthetics. We offer an option that’s natural; it’s grown from the earth,” added Wang.

MycoWorks can customize the Fine Mycelium sheet for variables like thickness and finish.

Using a design-patented tray, the material is grown for 4-5 weeks in an environment with precisely controlled temperature, humidity, and airflow. The natural organic ingredients are byproducts from the wood industry (essentially wood chips), hydration, nutrients, and the mycelium inoculum—the “spawn.” At the end of the process is a sheet of material peeled off a substrate. It is sent to European tannery partners with long histories of preparing leather for high-end applications.

“We carry over knowledge and expertise from the leather industry, but it’s entirely different for the cellular makeup of mycelium, which has its own signature grain and feel,” said Wang.

 

Pushing for Fine Mycelium scalability

While Fine Mycelium is used in just a few Sollei applications, Wang believes the “sky is the limit” for the materials applications.

“It’s a journey, so we’re starting with applications that make the most sense for where our material is today,” she said. “But the partnership with GM is a great long-term commitment to develop the material for any application that we can see today where you see leather.”

A major challenge for MycoWorks and its Fine Mycelium now is scalability. The company started in a small pilot plant in the Bay Area of California doing tens of thousands of sheets per year. It has now grown to a factory in South Carolina that’s over four times as large and is the first commercial-scale mycelium biomaterials operation in the world, according to Wang.

“We’re working towards our ramp-up right now, and it will have a capacity of millions of square feet of material in in the future,” she said. “To address the automotive market, we would need to grow that by many factors. But we’re on our way, and the partnership with GM is a foundation for that.”

 

Future automotive-spec applications

As a CMF designer, Dunbar is “always looking for what’s new and beautiful—and materials that we can try to bring in. These are things that we’ll put on our inspiration boards.” However, getting new materials into vehicles is a challenge.

She is excited that GM is willing to work with a company like MycoWorks that is not in the automotive space on a large scale.

“Automotive spec is extremely difficult to achieve, even for our long-standing automotive suppliers in many cases,” said Dunbar. “Even though the material isn’t currently reaching what that final automotive spec needs to be, we’re going to work with them to try to make it happen. It fits along with this very optimistic story of Soleil, so I thought it was a perfect opportunity to introduce the partnership to the world.”

Beyond the car, Dunbar is especially interested in exploring the material’s use in the accessory space on high-end vehicle concepts.

“I think those are amazing storytelling opportunities—to be able to use the same material in the vehicle and [for] accessory-type items,” she concluded.