July focus: Aerodynamics 

Wind tunnels have, in one way or another, been used in automotive design for the best part of a century. Created in 1924, the Rumpler Tropfenwagen was very much ahead of its time in this respect and drew on learnings from aviation. 

The result, quizzically, was a car that very much looked like a boat, with the flush sides of the main body tapering at either end to form a hull. While it would not preview the archetype for automotive aero (note the wide, flat roof and exposed wheels) it showed how even in the early days of the automotive industry, aerodynamics was more than a flash in the pan. 

More than 100 years later, the topic has re-emerged as a key consideration for designers and a subject of great interest to industry observers. 

It is difficult to cheat air, which will hunt for the path of least resistance as it flows over an object, but it can be guided through clever design either to reduce drag, improve downforce, optimise cooling or temper wind noise inside the cabin. Refinements to the exterior can be made physically in a wind tunnel or simulated through computational fluid dynamics (CFD), oftentimes a mix of both. 

This would go some length to explaining why anything that wishes to cut through the air (or indeed water) takes a similar end form. Push all other considerations to one side, and there is the 'ideal' shape: the teardrop. Evolutions of this can be seen elsewhere in nature, from fish that effortlessly glide through the water to birds diving for prey; the peregrine falcon at terminal velocity is a popular case study.

But if the trend has been ever present, why is interest in aerodynamics seemingly at an all-time high? As with most automotive design trends, it is largely a result of technology shifts. The latest has been the democratisation of electric vehicles (EVs) which have by all accounts completely re-shaped the product planning of OEMs big and small. 

Battery technology, at a broad level, has dictated how far an EV will travel. Early mainstream examples — the e-Golf, Nissan Leaf, Renault Zoe et al — did well as city cars or for short trips, but were hampered by real-world range. Highway driving would sap battery capacity at an alarming rate, and changes had to be made. Anything that could boost range had to be adopted. 

Much of the gains so far have come from cheaper, more energy-dense batteries and low-consumption electrical systems, but it became clear that drag reduction was also the next frontier for exterior design. Indeed, the language employed around new car launches has shifted over the past decade or more. Aero has almost become a buzzword such is its popularity, but it is a result of genuine utility and measurable results. So much so that recent press materials inspired the title for our recent livestream 'Sculpted by air'. 

Automakers have been openly championing range but also drag co-efficient (Cd). Concept cars like the Mercedes EQXX have been built with the explicit task of setting new records on both counts, and more recently, even 'normal' road cars are putting up Cd numbers that are not far off. Just look at the Tesla Model S (and 3), Nio ET7, Porsche Taycan, Mercedes EQS, Audi E-Tron, Aion Hyper GT, Lotus Eletre. The list goes on. 

The teardrop shape has been an easy route to procuring such strong Cd numbers, but there are only so many clones with different badges the industry can stomach. Homogeneity has become a common term, the merging of the 'aero' and 'crossover' trends creating a situation where brands are almost camouflaged among a mass of near-identical silhouettes (often with the same horizontal light bar, but that's another topic).  

This current period of aerodynamics-led design may be accused of copy and paste tendencies, but in some ways it has spawned its own typologies. Almost anything can be a fastback these days, dropping that roofline and taping its profile into more of that teardrop silhouette. The next challenge is to find new, exciting exterior designs that stand out from the competition while continuing to execute on those aero targets. Or perhaps it isn't. Could another technology shift that allows EVs to travel even further reduce the interest in aerodynamics and offer greater freedom to explore? 

From conversations, some designers already feel that interest in aero could soon peak. One designer at a large automaker told us that it is not really a priority at all. This will surely ring true for certain typologies as it has done in the past; a hardcore off-roader will prioritise other things, even if it is electric, and prospective buyers will respect that. For other segments? Things still seem to point toward an aero-first design, even for the off-roader's close cousin: the SUV. 

"What will probably happen with SUVs is they will try to be more efficient, so maybe slightly lower and better in terms of aerodynamics," noted Gilles Vidal this month, speaking at the time as Renault's VP of design (ed. Vidal has since joined/returned to Stellantis). 

But as mentioned earlier in this piece, it is not all about drag reduction. Performance cars road going or otherwise will employ certain features to help that car stick on the road or dig into tight corners. They might use certain openings and flaps to do this dynamically, and other considerations like brake and powertrain cooling are incredibly important. 

A recent conversation with Alpine's design boss Antony Villain revealed how the team is exploring new ways to hide certain garish aero attributes; the Alpenglow hypercar has a clear 'floating' rear wing that is in line with the wheel arches, totally hidden from side profile in comparison to its competitors. "We wanted to make it super subtle, super elegant and invisible," he told CDN. 

The Ioniq 6 N has some combination of both approaches, with a sleek teardrop profile but also enormous splitters and a very much in-your-face boot spoiler. A combination of the various aero considerations wrapped up in one road-going package. Indeed, aero might have risen in stature for mass market vehicles but it is in the performance bracket where focus remains highest. 

For Karma, which recently showed off the electric Kaveya supercar, aero continues to play a major role in its design."We’ve integrated aerodynamic benefits throughout, like the hidden cowl and the clean surfaces," notes design boss Nicholas David. "We also have classic aerodynamic features like the pass-through ahead of and behind the front wheels, and venting behind the rear wheels to relieve pressure."

For Lamborghini design boss Mitja Borkert, the key is to work closely with aerodynamics experts during the design process to find ways of preserving the brand's unique identity. "That relationship is critical," he told CDN. "Sometimes their technical requirements inspire ideas I wouldn’t have reached on my own. On the Aventador SVJ, for example, we added aerodynamic blades to the front cheeks, something that emerged through dialogue, not dictation." 

The key is to find that balance between aero and the original design intent, he adds. "Oftentimes, hitting 85 or 90% of the technical requirement is enough. Pushing to 100% can ruin the design. You end up with a potato."

Scott Krugger, head of design at Dodge and SRT, is of a similar opinion and told CDN in our recent livestream that working with aerodynamicists is ultimately fun, describing the process of "geeking out" as one of the more enjoyable elements of the job of late. 

Wind noise is also a crucial consideration for which aero-tweaking can influence for the better. Nobody wants a quiet cabin to be disrupted by roaring wind noise. Close attention to components like the wing mirrors, roof angle and prominence of the wiper blade can help this. This is not the 'sexy' end of aerodynamics, but an incredibly important factor that will be particularly relevant to premium and luxury marques. We noticed this earlier in the month during our time with a press loaner; the Xpeng G6 did well to block out wind noise but was let down by whirring from elsewhere. 

All things considered, this month's exploration of aerodynamics has led to some stimulating conversations and shone a light on some lesser-known considerations. We look forward to following the topic in our usual coverage, and hope the insight gathered from leading designers has served as inspiration for upcoming projects. Or, at the very least, as food for thought.