What Makes Rimac's Carbon Fiber Monocoque Unique

Mate Rimac says the C_Two will perform even better than first claimed, and their unique platform will only be shared with Automobili Pininfarina.

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Máté Petrány

A lot of work has been done since we last talked to Mate Rimac, and standing next to the Croatian EV company's long-term rolling chassis at the Geneva Motor Show provided the perfect opportunity to catch up on what's new. Mate told me that they've doubled in size in twelve months (the second time that's happened), with the headcount now being close to 550 people. They're also continuing their projects with Porsche, which is why the German giant made its investment last June.

As for the upcoming second Rimac model, the C_Two's development couldn't be more intense. While Mate would continue perfecting his car forever, his engineers are pushing for a design lock right around now, so they can start homologation and testing. One of Rimac's challenges is that they need to produce their first 30 prototypes at a rented intermediate facility, as their new campus won't be ready in time. They need a total of thirty test cars because they want to speed up the validation process, moving away from the boutique industry's methods by using the same processes as big OEMs. That means crash tests running simultaneously for Europe and the U.S., while other cars are ready for dynamic tests and assembly preparation.

Another problem with the C_Two is that it's “quite above the target weight” right now. One way of correcting that would be to replace 222 milled aluminum chassis inserts with 3D-printed titanium ones. But that would add $34,000 to their costs, and with the C_Two's business case "already being on the edge," Rimac is currently trying to find the right balance between making the car better, and raising costs. Otherwise, they just won't make any money on them. But Mate says no matter how they intend to fix the weight, they only have a further two or three months more to play, because once crash testing begins, nothing can be changed.

With that in mind, 200 engineers are working on the C_Two full time, so that the tooling can be ready 18 months before the first car is set to reach its customer. Mate says the C_Two project is "a marathon, and not a sprint," but the first real winner of this race seems to be Automobili Pininfarina.

Rimac needed to cut costs in half, and Mahindra's EV startup was the quickest to raise a hand, also being favorable from a brand perspective. As part of an exclusive deal, Automobili Pininfarina payed $91,000,000 to secure the C_Two's technology for their Battista, which combines the C_Two's chassis and powertrain with Pininfarina's luxurious body and interior. As Mate Rimac sums it up, that's "a significant help, because one needs to sell a lot of cars to make over 90 million."

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Máté Petrány
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Máté Petrány
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Máté Petrány

Mate also says that because their all-wheel drive electric platform with roughly 2000 horsepower on tap can replicate pretty much any car's dynamic behavior, the tuning of the C_Two and the Battista can be sufficiently different. Or at least as much as an Audi R8's compared to a Lamborghini Huracán's, and very much up to Pininfarina. But no matter where those two land on the "aggressive/luxurious" axis, Rimac's rolling chassis is something to behold on its own. Here's what Mate could tell us about it:

First of it's kind

It’s quite special. It’s a carbon fiber monocoque like lots of people have, but this is the first one with a structural battery pack integrated. And the battery modules are also structural. Then, it’s also a single carbon piece. It’s the only carbon monocoque like that. So, for example, a McLaren carbon tub is very small, while ours is very big, and the front and rear suspensions are on the same part. It’s one piece. A Porsche 918 or a Bugatti Chiron have subframes front and rear, and other supercars also have aluminum or steel add-ons, but ours is full carbon fiber, all the way from the rear crash structure to the front crash structure. What isn’t carbon is only designed for a crash. The front and rear powertrains are also integrated in the monocoque, so every important part is inside. The only bit outside at the front is the cooling system, a very complex one of that.

It's crazy

The car is not designed to be a Valkyrie competitor, I would say more of somewhere between a Chiron and a LaFerrari. So, it has to have the capability and the comfort of a Chiron. It has very large doors, and a monocoque that goes inwards, so you don’t need to climb across the sill to get inside, like in most supercars. And that seems like an obvious thing to do, but to have such a small sill with no roof above it, it’s very difficult from a crash perspective. As a whole, it turned out to be a very complex monocoque. We have people from Formula 1 working on this, and they said they’ve never seen anything like it. Just the lower part, without the roof is 2200 sheets (of carbon), and 222 metal inserts. It takes like two month to build one. It’s crazy. It needs multiple curings, going in and out of the autoclave four times.

Gordon Murray

What I’m telling my team sometimes is that people who worked on the McLaren F1, from that point on have their whole careers defined by that. They will always be remembered by that. And I think ours is the first proper electric hypercar. The Concept_One was nice, but we designed it as a very young company, and made a lot of mistakes, learning an equal amount along the way. But this is properly globally homologated, and the first of its kind. Nine years after I built the Concept_One for the first time. I think for the people working on it, the C_Two will be an important chapter in their career. It’s not just performance, it’s not just the numbers. It’s a tour de force of everything, and as such, a huge undertaking.

And you’ve guessed it: the platform is designed to work equally well without a roof.

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Máté Petrány
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