Cadillac's Future-Tech Flagship
2024 Cadillac Celestiq spearheads GM’s path to next-gen architectures, processes and propulsion.
Restoring the Cadillac brand to its golden-age pinnacle, when it stood equal among Europe’s ultra-luxury greats, has long been an intermittent dream within GM. The grandiose ‘Sixteen’ concept in 2003 earned praise, raised hopes, and narrowly missed production approval. Next year, however, another no-compromises Cadillac — electric, of course — returns to take on Rolls-Royce and Maybach in the battle of unbridled luxury. Each Ultium-powered 2024 Celestiq will be bespoke — hand-built in a dedicated facility located within GM’s Warren, Mich., Technical Center, and personalized to their “client’s” request.
With an expected MSRP to begin at more than $300,000, Celestiq can be a prestigious profit-earner for GM. Strategically, the dramatic- proportioned EV spearheads technologies that are expected to cascade across GM’s product portfolio. They include an architecture dominated by large aluminum castings; mass adoption of additive/3D printed components; sophisticated next-generation propulsion, advanced chassis control and interior systems, and GM’s UltraCruise automated-driving tech.
“What you see in this program [Celestiq] is impacting our technical direction in many others,” a GM executive engineer who requested anonymity shared with SAE Media. To date, the intellectual property around Celestiq includes approximately 300 approved and pending patented technologies and processes.
New customer, new processes
Experienced leadership is particularly vital for success in a clean-sheet vehicle program. GM kicked off Celestiq nearly four years ago with veterans Tony Roma as chief engineer, and Jeremy Loveday as program engineering manager. Roma cut his teeth in powertrain development and has many recent Cadillacs plus Camaro ZL-1 under his chief’s belt. Loveday’s first assignment at GM involved the pioneering EV1’s aluminum structure. He later dove deep into physical integration and later served on Cadillac XT4.
Both engineers have gained an understanding of the Celestiq customer and how that individual differs from XT6 or even Lyriq buyers. “These truly are people that tell you about a $100-million-dollar yacht that they spent three years building,” Roma said. “They don't see roadblocks. They don't understand the word ‘no’ like most of us do. And ‘I can't afford that’ doesn't enter their vocabulary. So, we've baked a mantra — “Never tell a customer ‘no’” — into how we make the car and the material choices. We just want to tell them how much and how long."
Celestiq’s development team was hand-picked by Roma in combination with management nominating the right people. “A unique program like this takes a certain mindset,” he asserted. “There is a lot of hand-to-hand combat on a daily basis” to execute two units per day within a huge, volume-focused organization. “We build prototypes faster than that,” Roma chuckled.
A Celestiq engineer is “somebody who is going to provide the answer even if it seems crazy,” Loveday added. He encourages a high level of communication within the engineering team. “We don't want folks who aren't enjoying it,” he said. “But like Corvette, the engineers on this program really are excited to be part of it.”.
The vehicle’s unique build plan includes aspects that remind Loveday of EV1. “We have a similar [plant floor] layout with eight main stations in a general assembly where operators have hours of content instead of seconds,” he explained. “It's not a moving assembly line. But where it differs is we're doing this ground up, in a brand-new facility, rather than using any in-plant carryover.”
Added Roma: “With Celestiq, we’ve challenged how we do things in every corner of the process — the way we purchase parts, how we engage with supplier quality, and the way we've engaged with manufacturing. We’re not fitting any aspect of this into existing processes. Every step of the way has been to take what we do that's good and make the ‘GM machine’ work for us. Our leaders have stood behind us every step of the way.”
That approach has meant using automation discretely where it impacts quality, such as setting glass. Mostly, the Celestiq shop floor activity involves humans picking up parts and using hand tools, Roma noted.
Extensive benchmarking included getting intimate with the competitive set. GM purchased a new 2022 Rolls-Royce Ghost, which followed a 2021 Bentley Flying Spur. “We wanted to thoroughly understand what it takes to play in this space and what’s expected there,” Roma said. He spent time in Europe talking with suppliers that serve the elite OEMs, learning how they and their customers operate.
“As we benchmarked, we got a feeling that it's really the same game we play at volume, only at a higher level. They still worry about complexity. They still worry about proliferation,” he explained. “It's just that they allow more of it because they're charging for more of it. It's a different business case.”
Valuable insights were gained during a visit to Multimatic by Roma and Rhonda Uhl, Celestiq’s Global Manufacturing Chief. The Canadian supplier is renowned for its innovative engineering and success in balancing high-volume programs with niche and performance customers. Multimatic famously handled the complete build of the 2018 Ford GT. Roma praised his Ford contacts for “graciously getting us in the door there.”
Casting a new architecture
Celestiq exemplifies how engineering helped deliver a design breakthrough: achieving a sleek, low-roof body with luxury seating for four, with the Ultium battery pack and electric propulsion system underneath. The learnings will be useful for GM’s future EV programs.
“In a lot of luxury cars, you have to sit in the back seat to get the best seat in the house,” Loveday observed. “We wanted all four of Celestiq’s seats to be top notch — 20-way adjustable with heat, vent, cool, massage and memory in all four places. But we recognized the challenge of getting the body structure to ‘mold’ around the battery and the occupants.”
Roma recalls a question he and others asked in the first team meeting: Can we use the battery pack from the Lyriq? “It’s flat, space efficient, and power dense but it’s also fairly tall,” he said. “We realized to meet the design vision, the Lyriq battery wasn't going to work.” Even with Celestiq’s Ultium cells oriented horizontally in the pack, the solution involved a vehicle structure using precision megacastings as a foundational element, enabling an appropriate rear chair height to accommodate the super-low roofline.
“The mega castings really lent the engineers and the artists a common ground. They were a natural fit,” Loveday said. “We use 6000-series aluminum for mass efficiency, put the strength where we need it. It proved to be very investment friendly for such a low volume car but also very package friendly.”
Roma explained that GM’s mega castings approach is different from that of Tesla (see here). Mainstream media have failed to accept that GM isn’t “following Tesla.” It’s been moving methodically to large structural castings; the 2017 Cadillac CT6 body structure used 13 Magna-produced castings, for example. But where die casting is economically feasible for high volumes, Celestiq production uses a gravity-sandcast process. “It delivers die-cast material properties from the aluminum alloys used, the way the molten metal is introduced into the mold, and from the heat-treat process,” he said.
Celestiq’s entire lower structure combines six of these precision sand castings, as shown in the accompanying illustration. The front and rear structures are connected longitudinally with two 8 ft-long (2.4-m) floor-pan castings that are spot-welded together then machined.
According to the engineers, each casting reduces the bill of material by 30 to 40 components, compared to typical fabricated construction. Improved package efficiency, rigidity and reduced cost are other benefits. “We’ve saved conservatively $100 million between manufacturing and traditional vendor tooling with our entire lower structure,” Roma noted. “This was our ‘epiphany’ moment for making our business case.”
The mega castings strategy has another upside: dimensional stability. “We got incredible stability metrics in our very first prototype body,” Roma reported, “data that’s as good as what we’d normally find exiting the prototype phase and entering the production phase. And that was the first body that we made! It's only gotten better from there, and that's blown us all away.”
Observed Sandy Munro, CEO of competitive analysis firm Munro & Associates: “The future is mega castings. We’ve done the math. lnvestment cost compared with fabrications is less. Bill of material is less. Rigidity is higher. Assembly is improved. Anyone not moving in this direction needs to find new consultants or talk to their internal financial people.”
While GM has been a leader in mixed-materials architectures, Celestiq body-in-white is 99% aluminum, Loveday said, “with a few steel inserts in the B-pillar for side impact. All castings are 6000-series AL; 5000-series warm-form AL is used on the one-piece body sides. The warm forming process employs a single die and keeps the aluminum near its melting point about 500 C (932 F). A puff of air over it enables the final shape of the part.
“Warm forming enabled us to achieve draft angles that were just unprecedented without any tearing,” Roma noted. Hot-stamped 7000-series AL is engineered into the upper structure for roof crush performance.
A 3D-printed showcase
When it enters production in late 2023, Celestiq will likely be the leading example of additive manufacturing (AM; 3D printing) in a production automotive application. The vehicle boasts 115 unique 3D-printed components, particularly interior trim, according to the engineers. The program became “a catalyst to accelerate the additive team” at GM, Roma noted.
“We've pushed them so hard to things like the D-ring on the front seat belts—that’s additive 316 stainless steel with an electroplated finish,” he said. “When we talked to them the first time about, ‘Hey, we want to do this,’ their reaction was like, ‘You want to do what? You want to make a safety-critical element out of a technology that we've never used before?’" Celestiq will launch with 47 interior parts made using additive stainless alloy.
Lavish cabin trim, in a mind-boggling array of materials and surface finishes, will be key to Celestiq’s extreme level of client personalization.
“Quality is the kind of thing when you see it, you know it,” Roma asserted. “The deco on the center console had to be commensurate with custom furniture in this vehicle. Every piece of brightwork on the interior is real, authentic metal. People have accused me of being obsessive about this, but Cadillac has to go above and beyond. Otherwise, people are going to come at this looking for plated plastic. We want to take away those excuses.”
Creating some of the customer-facing parts out of billet, or die casting, was the team’s backup plan. “Fail fast is one of our managements,” Loveday said. “So, we started 3D printing things. And it worked. And then we started to make them hollow, and it became more efficient.”
Celestiq’s AM push raised awareness of the process’s expanding capabilities within other GM vehicle programs. One of the program’s focal points is its 3D-printed aluminum steering wheel. “It’s a laser centering process,” Roma explained. “You break the support structure off, run a qualifying cut with a five axis CNC machine, then send it to the hand polish.
“We looked at doing a die casting,” he continued, “but with the dipole you can't get the B-side features that are needed for attachments and switches and all the other things. So, either you got to make the thing bigger and bulkier or use additive, which let us put the material just where we wanted.”
Roma admitted that using AM to make the steering wheel surround “isn’t exactly cheap; you won't see this on a high-volume car any anytime soon. But this is the literal ‘jewelry’ that's right in your face.” Perfect for the client who just spec’d out their $100 million yacht’s cabin.
“We’re absolutely going to drive our competitors crazy with what we're going to easily allow people to customize,” Roma said. “That would be impossible with other manufacturing methods and techniques.”
The program also used AM to print the sand cores for the body-casting molds. “We 3D-printed those cores before we hard tooled anything,” Roma said. “That’s incredibly powerful tech and not just for speed. We sent our rear suspension hollow cradle design over to our casting partner and in seven days we had a physical part sitting on the ground in Milford.”
Cool cabin and more
The engineers note that Celestiq does share proven, validated componentry with GM’s high-volume programs, in hidden areas of the vehicle where it made sense. “We partnered with Silverado EV and Hummer EV wherever possible,” Roma said. “It's no secret that anytime you partner up with a full-size truck program, you're going to get all the support in the world.”
One example is the HVAC module buried deep under the Celestiq’s dash. “We wanted a true quad-zone HVAC with four individual fan zones, modes, and temperature,” Loveday explained. “We came up with a modular design because not everybody wants a four-zone system like we’re using. It'll be validated and built in volumes that are two orders- of-magnitude higher than ours. We get to amortize the investment over volume.” Celestiq’s ‘ClimateSense’ microclimate system supplied by Gentherm features an array of sensors and controls that allow each occupant to personalize their desired level of seat heating and cooling.
A comprehensive technical review of Cadillac’s upcoming flagship will require plenty of future reporting as details are released and discovered. The vehicle’s Ultium-based propulsion system, combining a 111-kWh lithium-ion structural battery pack and a dual-motor, AWD driveline are expected to deliver roughly 600 hp (447 kW) and 640 lb-ft (868 Nm), with an 80% charge providing 300 miles (483 km) of range. Celestiq is fitted with a 200kW DC fast charging system capable of adding up to an estimated 78 miles (126 km) of range in 10 minutes.
Front and rear drive ratios (11.59:1 and 11.63:1, respectively) are unique to Celestiq, with ‘smart’ control of each axle. The flagship sedan also features regen-on-demand braking with a one-pedal function. Ride and chassis control systems will break new technical ground in a GM vehicle, according to engineers. But as satisfying as these features will be for Celestiq’s clients, their influence across GM’s vehicle programs will be profound.