10 Most Aerodynamic Cars: Exploring The Pioneers Of Automotive Aerodynamics

Moving a large piece of machinery on wheels is easy enough, but how to do it efficiently is a different story altogether. For cars, movement goes beyond simply having a means of propulsion, with several ways of achieving it as expeditiously as possible.

There's the matter of weight reduction for instance, to reduce the effort that the engine has to exert in setting a significant amount of mass in motion. Another way is by tweaking the powertrain to squeeze out as much power as necessary (and as cost will allow).

But one aspect that impacts both aesthetics and performance is aerodynamics.

Aerodynamics refers to how air behaves when an object passes through it, especially the way it results in forces that air exerts on the object's movement. This body of knowledge is part of a branch of physics known as fluid dynamics which covers the study of liquids and gases that move.

Don't be thrown off by the 'aero' part of the term, as aerodynamics involves anything that moves within a given atmosphere. Simply put, this field of study isn't just limited to machines associated with flight, such as frisbees, kites, aircraft, and rockets, but also includes land vehicles, such as motorcycles and cars.

There are four forces that affect the way an object moves through the air:

• Weight - The effect of the earth's gravity on a given object's mass. How strong the pushback against gravity should be depends on how much the object weighs.
• Lift - This is what pushes the object sufficiently upward to counter the force of gravity, serving as the opposite of weight.
• Thrust - The force that moves the object forward. In powered objects, this is provided by the engine.
• Drag - The opposite of thrust as the force that resists or slows a moving object down. Ideally, an object's thrust needs to be higher than its drag in order to sustain the forward motion.

The more aerodynamic an object is, the more smoothly it goes through the air since there will be less drag. When measuring how easily an object slips through the air, engineers use a number called the drag coefficient (measured as C_d), a value that determines how streamlined an object is to fight the effects of air resistance. The lower an object's drag coefficient, the lower the air resistance it encounters since it is observed to be more streamlined.

Shape (and, by extension, design) plays a critical part in how much drag an object comes across. A cube can have a drag coefficient of C_d=1.05, while a cone with the pointed end facing forward measures C_d=0.50. A half-sphere may have a drag coefficient of 0.42 C_d, but flattening it into a streamlined or teardrop shape results in a low drag coefficient of 0.04.

Most round surfaces are not as affected by drag as flat ones, and narrow surfaces are usually less prone to drag than wide ones. As a general rule, if there are more surfaces on an object hit by air, the result is higher aerodynamic drag.

Automakers want their cars to yield as much performance and efficiency as possible, both for sales and bragging rights. To that end, they want to minimize drag when it comes to design. This is because drag causes friction, something which increases the faster a vehicle goes, making the engine consume more fuel just to keep it moving.

But that's not all. If a car isn't aerodynamically optimized, it could produce a higher amount of wind noise, making even short journeys uncomfortable for occupants. And if insufficient downforce is generated in relation to the engine's power, the car could end up being unstable, making it dangerous to drive at high speeds.

In just over a decade since Ford's introduction of the Model T in 1908, engineers began to see the wisdom in reducing drag by improving a car's silhouette. These days, automakers rely on both computer modeling and wind tunnel testing to measure vehicle aerodynamics, sometimes used in combination with a rolling road to get more accurate results.

Electric cars are particularly susceptible to aerodynamics, relying on a low drag coefficient to improve efficiency and range.

There's a lot to take in where automotive design is concerned, and purpose plays a large part. Some forms call for interior space and versatility along with a smattering of visual intimidation. Meanwhile, others place a premium on speed, handling, and efficiency - apart from conveying a sense of poetry in motion.

As early as the 1950s, automakers were studying the effects of drag on performance vehicles. Current passenger cars typically have a drag coefficient ranging between 0.25 and 0.30 C_d, going up to 0.45 C_d for SUVs on account of their bulk. Let's take a look at some of the automotive standouts taking the automotive industry by storm at one point or another in terms of their ability to glide gracefully through the ether.

And don't be surprised to see a number of electric cars on this list, as they've become the poster children of aerodynamic design for production cars.

The 92 was the first production car by the now-defunct Swedish automaker. There's a good reason why this model was the pinnacle of four-wheeled aerodynamics for its time, as it directly benefited from Saab's history as an aircraft manufacturer.

Predating modern automotive aerodynamic technologies, the 92 instead packed aeronautical tricks such as a body stamped entirely out of a single sheet of metal and headlamps sitting flush with the bodywork. All these combined to give the Saab a drag coefficient of 0.230 C_d, unheard of in its time.

Toyota's long-running Prius holds the distinction of being the first mass-produced hybrid vehicle in auto history, along with ranking as the world's top-selling hybrid car as of September 2022, with 5 million units purchased by customers.

The fifth-generation model gets a size upgrade over the previous iteration in terms of length, width, and wheelbase. While this consequently improves interior space, the increased dimensions also had a slightly negative effect on aerodynamics as the new Prius delivers a drag coefficient of 0.27 C_d, some 0.03 C_d more than its predecessor.

Proof that aerodynamics isn't necessarily exclusive to performance cars, the Opel Calibra (also marketed as the Vauxhall Calibra) was regarded as the slipperiest production car in the world when it debuted in 1989. The drag coefficient of 0.26 C_d was a result of wind tunnel testing in the Netherlands, leading to tweaks such as a tapered rear waistline, shrunken panel gaps, and flush door handles.

However, this didn't last long as options like four-wheel drive, a V6 engine, and turbocharging on the Calibra's performance variants increased the drag coefficient to 0.29 C_d. Nevertheless, the Calibra held the title of aerodynamic mass-produced champion for the next decade until it was dethroned by the Honda Insight, which boasted a drag coefficient of 0.25 C_d.

Porsche's first series production electric vehicle brings a respectable drag coefficient of 0.22 C_d, made possible with cutting-edge 3D computational flow dynamics adapted from the design of the Mission E prototype. The Porsche Taycan is currently sold in four-door sedan and four-door station wagon body styles, with single- and dual-motor configurations.

Retractable door handles and spoiler combined with a relatively short nose embolden Porsche's claim of the Taycan's aerodynamics being the highest of any of the models in the automaker's stable. Only the Turbo S variant has a slightly higher drag coefficient of 0.25 C_d.

This midsize sedan with fastback styling is the second offering under Hyundai's Ioniq line of electric vehicles, itself spun off from the 2012 i-oniq series hybrid concept car that yielded the original Ioniq compact liftback in 2016. Hyundai's head of styling in China, Simon Loasby, says that the Ioniq 6 pulls visual inspiration from models such as the Saab Ursaab, Phantom Corsair, and the Stout Scarab, evident in the arching beltline and sloping roof.

These seemingly vintage streamliner influences work together to deliver modern aerodynamics, with the Ioniq 6 achieving a drag coefficient of 0.21 C_d. This is by far the lowest that Hyundai has to offer. Elsewhere, the design has also resulted in the highest scores for crash safety at Euro NCAP using criteria such as adult occupant safety, child occupant safety, and pedestrian protection.

Tesla's executive four-door sedan first broke into the scene in 2012, packing a drag coefficient of 0.24 C_d. Aero-wise, this made it sharper than the Prius for the same model year. The Model S would go on to post the highest sales of any electric vehicle worldwide in 2015 and 2016 until the Model 3 took the crown.

On its website, Tesla says that adjustments it made through the years have managed to shave the Model S drag coefficient to 0.208, claiming it to be the most aerodynamically efficient production car in the world. The sleekness of the Model S allows it to take full advantage of the performance benefits delivered by three electric motors on the range-topping Plaid trim, with a 0-60 mph time of 2.07 seconds.

Debunking Tesla's assertion of the Model S as the slipperiest production car available is the EQS Sedan, the electric contender from Mercedes-Benz. This electric full-size luxury liftback edges out its American rival by a nose with a drag coefficient of 0.202.

This has since been beaten by the Lucid Air, which claims a drag coefficient of just 0.197. That's better than the original estimate of 0.21, which was announced in 2020, proving that there is often room for improvement.

Back when automakers were still tentative about the idea of electric mobility, General Motors stepped up to the plate with the EV1. It was the first of its kind, both as a mass-produced model and as a purpose-built vehicle conceived as an electric vehicle at the outset. The EV1 was never sold but rather leased to customers, probably because GM was still unsure whether EVs were a profitable long-term investment.

The EV1 had room for only two occupants, which meant that GM could play around with its proportions for maximum aerodynamic effect. Its abruptly cut tail end gave the impression of a tall vehicle, yet the EV1 glided through the air with an unbelievable 0.19 C_d during its run.

Totaling 250 units, the XL1 was the third attempt by Volkswagen to come up with a series hybrid vehicle that could achieve maximum range on a single liter of fuel. In the case of the XL1, this was enabled by a plug-in hybrid powertrain supported by a common-rail turbodiesel engine. Despite the low output (68 horsepower), the Volkswagen XL1 rounded off its efficiency arsenal with a streamlined body made of lightweight materials.

The earliest prototype had a coefficient of drag amounting to 0.159 C_d, eventually settling at 0.189 C_d by the time the limited production version was released in 2013. This made it the most aerodynamic production car ever made (at the time). Volkswagen rated the XL1 at an incredible 260 mpg, which has since been revised to a still respectable 120 mpg under real-world conditions.

Fittingly, the most aerodynamic car on this list was a motorsport model: the Panhard CD LM64, based on the standard CD that already boasted a drag coefficient of 0.22 C_d thanks to its extremely aerodynamic form and fiberglass body. Intended for the 24 Hours of Le Mans, the LM64 carried over the production CD's chassis while replacing the stock rear leaf springs with coiled units.

Aerodynamicist Lucien Romani, who worked with Panhard designer Charles Deutsch (after whom the CD was named), made radical improvements to the LM64. Covering the headlamps, using spats on all four wheels, and placing two large vertical fins at the rear helped bring about a drag coefficient of just 0.12 C_d, a feat that remains unchallenged to this day.

And if you're wondering where the Lightyear 0 is, a solar-powered car claimed to have a C_d=0.175, the company may not even exist for much longer, so we haven't bothered.