No One’s Talking About the Best Part of the Bugatti Chiron

For all of its eye-popping figures, dramatic design and historic pedigree, the brand new Bugatti Chiron that debuted at the Geneva Motor Show yesterday seemed to elicit little more than a collective meh from the automotive media.

Perhaps it’s because the Chiron is, in many ways, essentially a nicely packaged evolution of its predecessor, the Bugatti Veyron. After all, the powertrain and transmission, though further optimized and improved, are directly carried over from the Veyron. Bugatti themselves say that they altered the Veyron silhouette only slightly for the new Chiron. There’s something to be said for not re-inventing the wheel, but there’s also something strange about turning down the opportunity to do something new, and opting instead to simply update the original. Better tires, better airflow, better structural rigidity — yes, sure. But better does not mean the same thing as new. Perhaps this is less of a Chiron and more of a Veyron Super Sport… Plus.

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Or, perhaps, we’re just not looking in the right places.

Because as far as I can tell, the Bugatti Chiron will become the first production road car to ever feature an exhaust-blown diffuser. Bugatti confirmed that the Chiron will feature six exhaust tubes: four of which dispel gasses normally through the back of the car; two of which send gasses out either side of the car, and downward, to increase downforce and therefore, grip. In F1, that hot air mixed with the air flowing below the underbody, heating it up and directing it toward the rear diffuser, where it creates the most possible downforce and allows the car to carry far more speed through corners than would otherwise be possible. Basically, it does everything that people who buy aftermarket body kits think they’re doing.

The blown diffuser idea has influenced Formula One going back to the 1980’s and famously fueled Red Bull’s rise to prominence in recent years (the lengths to which Red Bull and chief engineer Adrian Newey went to develop and then hide their technology is truly astounding), but was banned after the 2013 season and has never even sniffed a street-legal setup. Until yesterday.

For some reason, this doesn’t seem to be as intriguing to others as it is to me. So far, I’ve found only passing references to it in the initial press reports (there aren’t photos, either, but that’s likely because the body hides it). And that’s all the more surprising, considering how pivotal the technology has been to Formula One over the years.

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This is where things get tricky, however, because as revolutionary as this idea is in a road car, it opens up a potential floodgate of issues and questions in a practical setting. And while the astronomic horsepower and punishing acceleration times are its most buzzworthy topics, the potential impact of the blown diffuser on the Bugatti Chiron could easily become its most distinguishing feature.

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For one thing, how much does the exhaust-blown diffuser act like those that were used in F1? Before the exhaust-blown diffusers were banned during the 2011 season, they created unheard of levels of downforce, but they also forced engineers to find ways to keep the throttle open in order to keep sending exhaust air toward the diffuser. This caused some issues that could easily become problematic in a road car: excessive heat and Escaladian fuel consumption. As well, the infamous “farting” noise that F1 cars pumped out at the time. In endurance racing, fellow VW brand Audi (more on that later) ran a blown diffuser on its R18 prototype that may have actually expelled that gas through the wheel wells. It too, was banned, during the 2013 season. Though the R18 was using a turbodiesel engine that would have reacted very differently to such a concept than a gargantuan 8.0L quad-turbo W16, it presumably would have produced a similar effect.

For another thing, is the blown diffuser active at all times, or only in certain driving modes and situations? The new Chiron is equipped with five driving settings: Life, EB, Autobahn, Handling and Top Speed. Putting around town in your new $2.5 million Chiron in any of those first three settings would not only be quite useless, they could be dangerous. Namely, coming on and off the throttle when you’re, say, entering a freeway on-ramp, will cause rapid changes in the amount of downforce sucking the car to the ground. Keeping the throttle open made the airflow consistent in F1, but doing so seems inconceivable in a road car — even one so ostentatious as this. As a result, imagine a Chiron owner taking a spirited entry onto a giant looping on-ramp, then deciding the speed is too much, and backing off the gas. One second, the downforce is there. The next, it’s not. Chiron, meet barrier.

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It also wouldn’t make much sense to enable blown rear diffusers in Top Speed mode. The effect only really works as it’s supposed to in corners, and the entire point of Top Speed mode, obviously, is to test the limits of the Chiron’s straight-line performance. So it would make sense to limit the use of the blown rear diffuser to Handling mode, which makes it a very expensive mode indeed to warrant the research, design and implementation of two additional exhaust pipes (and developing software to control the technology) all for a little occasional track time. Does Bugatti expect Chiron owners to track their cars a lot more than the Veyron? Unlikely. Does Bugatti have secret racing aspirations with the Chiron? Even less likely. Does Bugatti see this as the first step in some kind of potential future, more widely accessible implementation of exhaust-blown diffusers?

This is where I think it gets interesting. As we all know, mass-production giant Volkswagen owns Bugatti, as well as a slew of other esteemed brands such as Lamborghini, Porsche, Audi and SEAT. Could VW brass be eyeing a potential introduction of exhaust-blown diffusers into its other cars? Granted, any road car would face the same concerning and flat-out dangerous issues that I’ve already outlined above, at a price point that could make an unknown technology concerningly accessible. And it does seem premature to speculate on this kind of plan when all we have to go on so far is a brief mention in a Chiron press release. But it sure would make the investment of developing such a technology for the road a whole lot easier to swallow.

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Either way, the decision to try an exhaust-blown rear diffuser in the new Bugatti Chiron is nothing short of truly daring and innovative. I will be especially eager to hear how it operates, and how it affects the performance of the car once the first official tests and driving experiences start to roll in. Because at the moment, it begs a monsoon of questions that will have wide-sweeping ramifications on the way we view the Chiron. I’m still surprised to see it confirmed, and surprised further that there hasn’t been much chatter about it thus far. Something tells me, though, that we’ll end up looking back at the Chiron as the starting point of a trend. Whether that’s ultimately good or bad, I guess we’ll just have to wait and find out.

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Ryan ZumMallen is a journalist in Long Beach, CA. Follow him on Twitter, here.

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