Cars are getting ever-more aerodynamic. The magic figure is a car’s Cd, or drag coefficient. The lower this is, the slipperier through the air it will be.
The less a body ‘drags’ through the air, the less energy it needs to keep it moving. With long-range electric cars on the horizon, and manufacturers under ever-greater pressure to cut the consumption of today’s cars, aerodynamics have never been more important.
With this in mind, let us show you which are the most aerodynamically efficient new cars on sale right now. These are, literally, the best motoring wind-cheaters you can buy today.
New 2019 A-Class Saloon takes the crown for most aerodynamic car
Details of the new Mercedes-Benz A-Class saloon have been announced, and the German company can be proud of taking the record for the most aerodynamic production car on sale.
A drag coefficient figure of 0.22 Cd, combined with a compact frontal area of 2.19 metre-squared, sends it straight to the top of the pile, and has been achieved thanks to detailed work in the wind tunnel. From an enclosed underbody to avoid disrupting the airflow, to ensuring the headlights seal flush with the bodywork, the efforts of the engineers has been huge.
Set to go into production at the end of 2018, the four-door A-Class will be built at the Aguascalientes factory in Mexico. However, if that is just too long to wait, we have listed the other 21 most aerodynamic cars you can buy right now.
2013 Mercedes-Benz CLA BlueEfficiency – 0.22 Cd
Much like how Mercedes-Benz keeps winning the Formula One World Championship, the Stuttgart brand only had itself to beat for the prize. The CLA four door ‘coupe’ set the previous record for the most aerodynamic car on sale back in 2013.
That the new A-Class Saloon looks rather similar to the CLA is perhaps no coincidence, with Mercedes combining evolutionary styling with aero knowledge. The BlueEfficiency model featured design elements such as a specially designed exhaust silencer and rear spoiler.
2017 BMW 5 Series EfficientDynamics Edition – 0.22 Cd
In common with many of the cars featured on this list, those which top the charts for aero efficiency are often special models built for lowered CO2 emissions. The pursuit of greater fuel economy and carbon output has forced manufacturers to spend even longer in the wind tunnel.
Developments like active shutters for the trademark kidney grille, and aerodynamically enhanced alloy wheel designs, are some of the tools used by BMW to reduce drag on the latest 5 Series saloon.
So, despite a Cd of 0.22, why do the two Mercedes beat it? Because it’s a bigger car with a larger frontal area. In use, the two Mercs will marginally be that bit more slippery. When cars are this aerodynamically efficient, every fraction counts…
2017 Tesla Model 3 – 0.23 Cd
Not having a conventional combustion engine to cool and feed oxygen to gives car aerodynamicists far greater freedom when it comes to design. No more gaping grilles means smoother airflow, which is important when you need to extract every last mile from your battery.
As the smallest Tesla, the Model 3 has all the aero technology from its bigger brothers, but in a condensed package. We can only speculate that the large panel gaps seen on some finished production Model 3s are intended to let the air flow more efficiently…
2018 Audi A4 2.0 TDI Ultra – 0.23 Cd
Another German car, another one aimed at the fleet market to ensure the lowest possible amount of CO2 emissions. Audi’s ‘Ultra’ range was developed from the all-conquering Le Mans prototype racers, where aerodynamics are rather important.
Whilst the 150hp 2.0-litre diesel Ultra model achieves an impressive 0.23 Cd, its petrol-powered TFSI brethren can only manage 0.27 instead. Who says that diesel is done for?
2016 Mercedes-Benz E-Class Saloon – 0.23 Cd
Mercedes-Benz has a wind tunnel and they’re clearly not afraid to use it when it comes to refining their range of saloon cars. In fact, it was the E-Class from 1984 which marked the start of Stuttgart’s obsession with reducing drag.
That car from over three decades ago managed a Cd figure of 0.27, thanks to a tapered rear end and a discreet boot spoiler. Despite the latest E-Class being notably larger, advances in aero design mean it surpasses its predecessor with an impressive 0.23 figure.
2016 Tesla Model S – 0.24 Cd
Much of the design language used on the smaller Tesla Model 3 was inherited from the larger Model S. As such, that the older, bigger, car is aero efficient should come as no surprise.
Work was put into ensuring air flowed smoothly around the front wheels, given that this area has massive implications on drag. Testing by independent magazines and websites has also confirmed that Tesla’s 0.24 Cd figure is accurate.
2016 Toyota Prius – 0.24 Cd
The teardrop shape on the latest Prius is nothing new, but the fourth-generation car underwent significant changes to improve on its predecessor. The roofline was moved forward, and extra underbody panels were added to find further aero efficiency.
It worked, meaning that despite the aggressive lines and angles, the newest Prius betters the old version by 0.02 Cd. In the world of maximising fuel economy, that tiny number can mean a massive difference in range.
2016 Hyundai Ioniq – 0.24 Cd
It should be no surprise that Hyundai’s big rival for the Prius is clothed in a teardrop-influenced shape. Designed to channel air effectively over the hatchback body, there are multitude of deliberate contours and creases on the Ioniq.
With three different versions of the Ioniq available, Hyundai has distinguished between the hybrid and pure electric models. Hybrids feature a three-stage active front grille, whilst the electric version uses a sleeker solid fascia.
2017 Mercedes-Benz S-Class – 0.24 Cd
We perhaps shouldn’t be surprised to see the grandest of Mercedes-Benz four-doors still managing to achieve the same aerodynamic efficiency as smaller hybrid hatchbacks. The German firm has simply applied its aero knowledge to more metal.
One key feature is that the gaping front grille features shutters to direct airflow as needed. Using air to cool the engine only when necessary has a major impact on efficiency.
2015 BMW 7 Series L – 0.24 Cd
By now you should be sensing a theme, especially when it comes to German cars from the same manufacturer. That the 7 Series looks similar to the smaller 5 Series should mean that its aerodynamic performance is likely to be almost as impressive.
A notable attribute of the 7 Series is active air suspension. Engaging Sport mode means the ride height of the largest BMW is lowered, aiding aerodynamic efficiency. There are also the requisite grille shutters and air curtains to help the big four-door along.
2018 Tesla Model X – 0.25 Cd
Aside from the Model X, you’ll notice there is a general absence of luxury SUVs on this list. Their taller, boxier, shapes make cutting through the air harder so aerodynamic efficiency naturally suffers.
The Model X has the advantage of not having a big engine up front to cool, and also features a streamlined body like the rest of the Tesla range. For comparison, a Hummer H2 only achieved a Cd factor 0.57…
2016 Kia Optima Hybrid – 0.25 Cd
With an emphasis on maximising fuel economy from the combination of battery power and combustion engine, the Optima Hybrid benefits from a number of bespoke modifications.
By now you’ll be able to guess some of the exterior elements that help the Optima Hybrid. There’s an active front grille, a special front air curtain, and model-specific rear bumper. Don’t forget the unique alloy wheel design, too.
2018 Mercedes-Benz A-Class Hatchback – 0.25 Cd
The new A-Class hatchback may have beaten its saloon brother to the market, but it cannot quite match the four-door when it comes to aerodynamics. The stumpier tail of a hatchback disrupts the air more than a sleek saloon, causing more drag.
However, the new A-Class is still one of the best hatchbacks on this list, so we’re sure Mercedes-Benz isn’t too concerned.
2018 Ford Focus Saloon – 0.25 Cd
Proving the point again that saloons outperform hatches when it comes to drag coefficient is the new Ford Focus. The fourth-generation hatchback appears a little later on our list, but it’s the four-door which scores better.
Ford introduced technology such as active front grille shutters on the previous-generation Focus, and has clearly worked hard to ensure the new model improves things further. The only downside? UK buyers won’t be offered the chance to buy the Focus saloon.
2018 Mercedes-Benz C-Class Saloon – 0.26 Cd
We challenge you to try and act shocked about seeing the latest C-Class saloon make this list. Those all-important active front grille shutters play a big part of the compact four-door, as will the countless hours spent in the wind tunnel refining the design…
2018 Audi A6 – 0.26 Cd
Aside from making all versions of the new A6 saloon mild-hybrids, Audi has also ensured that it comes close to the aerodynamic ability of rivals from BMW and Mercedes-Benz.
Improving fuel economy matters to executive buyers, but so does a quiet interior. Ensuring air flows smoothly around the car helps reduce wind noise, making the experience in the cabin more refined.
2014 BMW i8 – 0.26 Cd
Along with SUVs, you may also notice that this list lacks flame-spitting supercars. Much modern performance machinery is focussed on generating downforce to aid faster cornering, rather than simply letting air flow smoothly across the car.
As a plug-in hybrid the BMW i8 is already different to make performance cars, so that it has an aerodynamically efficient shape is expected. BMW used fluid dynamics to create the i8’s shape, with cut-outs and air curtains galore. It all clearly worked.
2017 Audi A8 – 0.26 Cd
Another big German saloon, and another one that manages to limit the drag coefficient it creates. Audi’s latest flagship is packed with new technology, and features styling intended to demonstrate poise and purpose on the street.
Autonomous driving capabilities might be the big sell for the A8, but aero cleanliness is still important. Despite the bold front grille, the new A8 still manages to be aerodynamic through a number of detailed tweaks, like specially designed exterior mirrors for less drag.
2016 Mazda 3 Saloon – 0.27 Cd
Compared to many major manufacturers, Mazda has taken a different approach when pursuing the need for improved fuel economy and reduced emissions. The brand’s latest SkyActiv engines use low compression to achieve greater efficiency, and are matched with the swooping styling of the latest Mazda 3 saloon.
Predictably the four-door model outperforms the hatchback version, and proves that Mazda’s distinctive ‘Kodo’ design language can be both handsome and low on drag.
2018 Ford Focus Hatchback – 0.275 Cd
Ford had made bold claims for the new fourth-generation Focus, touting it as ‘the best car’ the company has ever built. Those are strong words, but the leap forward in technology and design keeps the latest Focus at the top of the pile.
As with the saloon version, features like active grille shutters help to reduce aerodynamic drag. Ford can be pleased with the fact that, A-Class and EV eco-warriors aside, it’s the best-performing family hatchback on our list.