There are three groups of people that are excited about the all-new BMW 7-Series. Journalists who will get to flog them around tracks and will get unbelievably excited when Alpina works its magic of them. Captains of industry that consider the Mercedes S-Class too formal and the Maserati Quattroporte too unhinged and, of course, the fans that know that will depreciate like a rock five years down the line and bring them within the realm of possibility.
That’s the group I’m concerned about.
Having been a Computer Science major, I always get positively giddy about new technology. Unless that technology is used for something idiotic (like the selfie stick), or if it seems to be built with the express purpose of making it easier to share the food you eat. So when manufacturers decided that their mainstream offerings would incorporate more and more fancy composites in their construction my inner geek was giddy with excitement.
The Alfa 4C is already there with its carbon-fiber monocoque in a reasonably(ish) priced sports car but for the rest of us it’s BMW taking the lead with their visionary i3. Here’s a car with an internal structure and body panels made out of CF for under $50k. You would’ve been labeled a loony if you had said that in 2008 or thereabouts this would be possible. But it really is here and, although BMW themselves have admitted that the process hasn’t gone completely according to plan. It seems that they’re completely set on this new path to make their cars better and stronger.
Then I remembered something that has been stored in my head for a couple of years now and that made me cold when I remembered this is what is coming to the structure of our cars. Unlike Steel or Aluminum, when Carbon Fiber reaches the limits of its tolerance, it snaps instead of bending. The word ‘Snap’ is not particularly comforting or confidence-inspiring, especially when it comes to something that’s going to become ever more common in the structures of our cars.
Yes, Carbon Fiber has more tensile strength compared to steel or aluminum, meaning it’ll take more force to break it than it does to bend steel or aluminum. But once it does, that’s it. You can’t just take it to your body shop to be straightened back into shape. You can choose between gluing it back together (which somehow sounds even less confidence-inspiring and concocts visions of a car held together with Elmer’s Glue, even though I know that’s not the case) or replacing the piece (Buy a new Passenger cell, how expensive can it be?)
Hopefully the joys of Moore’s law will apply to these components and they will become cheaper as time goes on. Otherwise, come 2023 when you see one of these 7-Series for around 20% of the price of a new BMW 780Li (Fitted with a Quad-turbo 2.0-liter four pot) you’ll have to be extra thorough when checking its history for any accidents, lest you accidentally buy a cracking car instead of a cracking good car.
The good side is that with Carbon Fiber being so strong scenes like this will become more common, and you’ll finally be able to shut someone up at a scene of an accident by saying “See? They *do* build them like they used to.”
Header Image Credit: BMWBlog
Outsider’s Perspective: Will the new 7-Series crack under pressure?
It’s no wonder that the i8 is so strong. They’ve stuffed an entire Porsche 911 in under there for crash absorption.
Carbon fiber repairs are patch-and-glue instead of patch-and-weld. It’s just a different approach and a different skill set. Just like metal body damage but not a crunched unibody will be repaired, carbon exterior damage but not always carbon structural damage will be repaired. The SE Composites guys, who do a lot of work for us, also do a lot of carbon bicycle repairs, but they specifically will not do forks, because it’s too critical and too delicate a part. Frames get repaired, forks get thrown away and replaced.
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