Contents
Less air resistance, more efficiency
Aerodynamics at Mercedes-Benz: added value
Increased range, safety and comfort
Aerodynamics at Mercedes-Benz: aerodynamic disciplines
Advanced measuring devices and modern methods
Aerodynamics at Mercedes-Benz: wind tunels and measuring devices
From a teardrop car to the VISION EQXX
Aerodynamics at Mercedes-Benz: history
The descriptions and data in this press kit apply to the international model range of Mercedes-Benz. Details may vary from country to country.
Less air resistance, more efficiency
Aerodynamics at Mercedes-Benz: added value
- Diverse advantages in everyday driving: increased range, comfort and safety
- Long tradition of aerodynamic design and modern measuring equipment
- Detailed aerodynamic optimization: the new CLA with EQ Technology
Low air resistance means high efficiency. This makes aerodynamics crucial, especially for electric vehicles. Reducing the drag coefficient by just 0.01 increases long-distance range by approximately 2.5 percent. Based on an annual mileage of 15,000 km (9,321 mi), corresponding aerodynamic optimization results in an extra 375 km (233 mi) of range.
Mercedes-Benz recognized early on that aerodynamics are key to efficiency. Accordingly, the list of models with top aerodynamic performance is long. It initially ranges from the 19371 W 125 to the 1938 540 K “Streamliner” and the C1112 from the 1970s to the W124 in 1984, which with a Cd of 0.29 was the first production car to fall below 0.30. More recently, the 2014 CLA Coupe with a Cd of 0.22, the EQS with 0.20 and the new CLA with EQ Technology with a class-leading 0.21. Another aero champion is the VISION EQXX. With a Cd value of 0.17, this technology platform features even less air resistance than an American football. While the focus of the VISION EQXX was on efficiency itself, the CONCEPT AMG GT XX was primarily focuses on efficiency at speeds of over 300 km/h (186 mph). A Cd of 0.19 and intelligent aerodynamics contributed to the AMG securing 25 long-distance world records on the Nardò test track in August 2025.
Previously, and especially in motorsport, achievable speeds and high cornering speeds, i.e., downforce, were the focus. Today, the main focus is on energy consumption and range while maintaining Mercedes’ renown driving characteristics. This also includes other aerodynamic disciplines of aeroacoustics, keeping the vehicle clean, and open-top driving comfort, which Mercedes‑Benz models have been at the forefront for decades. The “Large Wind Tunnel” in Untertürkheim was the world’s first of its kind for automobile development. The first documented measurement took place there over 80 years ago on February 5, 1943. The “Large Wind Tunnel” is still in use. In 2013, Mercedes‑Benz once again took the lead in aerodynamic testing with the aeroacoustic wind tunnel at the Sindelfingen Development Center.
Small details, big impact: aerodynamic optimization of the new CLA
As great as the added value is in everyday driving, the aerodynamic optimizations of the vehicles are just as extensive, for example, with the all-new electric CLA. With a Cd from 0.21, the all-electric CLA is one of the best in its class. Within the model series, the spread of Cd values is also minimal. This is partly due to the wide range of aerodynamically optimized wheels. These include, for the first time, a bicolored full cover for alloy wheels. Compared to a conventional wheel, it performs up to 15 Cd points better; compared to an already aerodynamically optimized aluminum rim, the advantage is still up to two Cd points. In addition, the aerodynamicists optimized the wheel spoilers forward of the front and rear axles, taking into account all available wheels sizes to minimize the influence of the wheels and tires on air resistance. In the area around the radiator grille and headlights, the joints were optimally placed and partially sealed.
The underbody concept of the EQS and EQE has been further developed. The smooth underbody is almost completely closed and the suspension control arms and tie rods are also covered. The rear wheel cover is fixed to the body shell, so it has no joints to the surrounding components and therefore does not move with the axle when it compresses, for example.
Increased range, safety and comfort
Aerodynamics at Mercedes-Benz: aerodynamic disciplines
- Most important lever for efficiency: flow optimization
- Crucial for long-distance comfort: aeroacoustics
- Contribution to active safety: keeping the vehicle clean
On long-distance journeys, aerodynamics is by far the biggest influencing factor on efficiency. One point in the Cd value, i.e., one thousandth (0.001), is equivalent to 10 kg (220 lbs) of weight saving in the WLTP cycle. Or, to put it another way: one Cd point less means approximately 1 km more of electric range (WLTP) for electric cars. A lower Cd value is particularly advantageous at higher speeds and contributes to Mercedes‑Benz’s customer-oriented “Real Life Efficiency” philosophy. This is because air resistance increases with the square of the speed. This means if the speed doubles, air resistance quadruples.
The dimensionless drag coefficient Cd is the measure of the aerodynamic quality of a body and thus also of an automobile. The so-called frontal area indicates how much frontal area a car presents to the wind. Previously, it was determined by projecting the shadow of the body with a very distant lamp onto a transparent screen. Then the outline was drawn and the total area was calculated from the individual segments. Today, the frontal area is scanned with laser light barriers. The frontal area multiplied by the Cd value is the air resistance.
Good flow characteristics make a decisive contribution to low energy consumption under everyday conditions. But safety, comfort and the environment also benefit from the elimination of disruptive air turbulence. Low lift values ensure good handling stability, and low wind noise provides long-distance comfort.
Mercedes-Benz optimizes the flow characteristics of vehicles down to the smallest detail through a large number of calculation loops, simulations and measurements in the wind tunnel in Sindelfingen. In addition to the external shape, numerous smaller measures also lead to top aerodynamic values. These include a reduction in frontal area, an extensive sealing concept and the underbody panels. Special wheel spoilers at the front and rear often help to ensure that the air flows around the wheels with as little loss as possible. Aerodynamic fine-tuning also takes place on wheels and tires. In addition, a louver system behind the radiator grille is available on many models, which regulates airflow through the engine compartment based on cooling requirements. This avoids unnecessary airflow to help maximize efficiency.
For early-staged optimizations: extensive simulation
While airflow behavior was optimized in early development phases using models in the old wind tunnel in Untertürkheim, this fundamental work is now carried out exclusively with simulation. Already at an early stage, the three-dimensional flow field that fundamentally surrounds vehicles is calculated on high-performance simulation clusters using CFD (Computational Fluid Dynamics).
Shortly after the start of the project, in the phase of the dimensional concept, several extensive DOE (Design of Experiments) studies with up to 250 calculations per study are usually carried out based on the predecessor. The aerodynamics engineers specify the parameter space of certain components, e.g. for the possible height of the trunk lid.
Such a DOE study takes several days and completely covers the specified parameter space. Based on these simulations, a global or local optimum can then be calculated, or, much more importantly in this phase, the influence of the individual parameters and its mutual dependencies on air resistance can be determined. With the help of the DOE method, concrete aerodynamic requirements can be reported and discussed with the employees in the area of dimensional concept as well as with the design department at this very early stage.
In recent years, the aerodynamics experts at Mercedes-Benz have intensively further developed the automated calculation processes including DOE. The path to the aerodynamics world record of the EQS required several 1,000 calculation runs in the virtual wind tunnel with approximately 700 CPU cores per calculation.
For a quiet interior: Aeroacoustics and psychoacoustics
In aeroacoustic development, Mercedes‑Benz focuses on two key aspects. As little noise as possible should be generated at the source, i.e., when the air flows around the vehicle’s outer skin. As early as the early development phase of a new model, the engineering team therefore begins to design the geometry dimensions that are particularly relevant for this, for example on the A-pillars and exterior mirrors.
The pre-design is carried out using a Computational Fluid Dynamics (CFD) simulation, with detailed simulations on particularly critical vehicle areas and with the help of our own 1:1 models in the aero wind tunnel. In combination with an array of 350 microphones, local sound sources on the vehicle’s outer skin can be made visible in three dimensions. In this way, even the smallest details in important areas can be developed at an early stage.
The quality of the vehicle’s seals and sound insulation makes a decisive contribution to ensure unavoidable wind noise is eliminated or highly minimized in the interior. A basic prerequisite for a low wind noise level in the interior is wind-tight door and window seals. This applies in particular to vehicles with frameless side windows.
The human ear is a master of localizing disturbing noises. Therefore, Mercedes‑Benz also specifically investigates the psychoacoustical relevant effects and localizability of disturbing noises. Based on tests with test subjects, the company’s experts have even defined their own target index. Its weighted measured variables cover the entire frequency spectrum of human hearing. For example, the following variables and effects are given consideration:
- Loudness [sone]: Representation of human loudness perception
- Sharpness [acum]: Classification of noises from dull to sharp, higher-frequency components significantly influence sharpness
- Articulation index AI [%]: Speech intelligibility, focusing in particular on the area of best human hearing. The higher the value, the better conversations can be held and understood
The measurements are usually carried out in the wind tunnel with binaural artificial heads. There, the microphones sit in simulated ear canals, which allow for ear-accurate recordings. Depending on the phenomenon being investigated, the artificial heads sit in the driver’s position or take a seat on the other seats in the vehicle. The measurement results then provide a realistic indication of how loud or quiet, disturbing or pleasant the passengers perceive the noise in the interior. With binaural artificial heads, even the smallest weak points can be specifically located, which are then eliminated as best as possible by technical solutions.
For a clear view: Keeping the windows clean
Having the cleanest possible windows and exterior mirror glass and thus optimal visibility under all conditions contributes to safety. For this reason, the aerodynamic discipline of keeping the vehicle clean is always given special attention at Mercedes‑Benz. In order not to burden the highly sensitive measuring technology and the running belts of the aeroacoustic channel in Sindelfingen with contamination tests, these are still carried out in the “Large Wind Tunnel” in Untertürkheim.
Contamination can be caused by rain, vehicles in front or droplets whirled up by the vehicle’s own wheels. In the wind tunnel, this contamination is made visible with the help of fluorescent liquid. The aim of the development work is to direct the water in such a way that the relevant fields of vision ideally remain clean. For this purpose, the aerodynamicists optimized, among other things, the contour of the A-pillars with integrated components as well as the shape of the exterior mirrors and window frames or the trim strips on frameless side windows.
Minor geometric changes to the mirror housing and detailed optimizations with seals and a special water deflector strip can significantly reduce contamination on the side window. Mercedes‑Benz has the requirement that there must be no impairment of visibility due to spray, rivulets or individual drops of water in the core viewing area of the side window and on the exterior mirror glass.
Draft-free open-top comfort
In convertibles and roadsters, the aerodynamicists at Mercedes-Benz pay particular attention to what is known as draft-free comfort, i.e., an interior that is as wind-free and pleasantly tempered as possible. For example, the CLE Cabriolet comes standard with AIRSCARF® neck-level heating and the AIRCAP® electric wind deflector system. Both systems make open-top driving pleasant even in cool weather. The AIRSCARF® surrounds the neck area of front occupants with pleasant warmth even in windy conditions.
AIRCAP® can be extended at the touch of a button to significantly reduce air turbulence in the interior of the CLE Cabriolet. The system consists of two components: a wind deflector that can be extended from the windshield frame and a wind deflector that extends behind the two rear seat headrests.
When extended, however, AIRCAP® is a potential source of wind noise. Aerodynamicists spent an extensive amount of time in the wind tunnel fine-tuning the design of the system and its surroundings, thus reducing the noise to a minimum. The experts optimized, among other things, the choice of mesh fabric, the geometry of the fin, and other radii and shapes. The way air flows through the mesh fabric and how both AIRCAP® components interact was also investigated and adapted to customer needs.
Advanced measuring devices and modern methods
Aerodynamics at Mercedes-Benz: wind tunnels and measuring devices
- Storm on command: wind tunnels in Sindelfingen and Untertürkheim
- Weather as desired: climate wind tunnels
- All ears: microphones and measuring dummies
The experts at Mercedes-Benz have optimized the aerodynamic properties of new vehicles for decades. Advanced measuring equipment and methods contribute to this, including the aeroacoustic wind tunnel in Sindelfingen. With excellent flow quality, very low background noise, sophisticated road simulation and high efficiency, it set new standards when it was commissioned in 2013. The facility is still one of the most powerful and quietest of its kind in the world. It also offers a particularly high level of simulation quality.
The wind tunnel follows the “Göttingen design,” which means that after the measuring section, the air is directed back to the blower and accelerated again, which saves a lot of energy. The blower has a diameter of 29.5 ft (9 m) and has 18 blades that set the air in motion. With a maximum torque of 149,099 lb-ft (202,150 Nm), the electric drive motor has about a thousand times the torque of a small car. At a wind speed of 155 mph (250 km/h), power consumption is five megawatts. The blower then rotates at 238 rpm and the volume flow then reaches 2,000 m³ or about three single-family homes per second. The maximum wind speed is approximately 165 mph (265 km/h).
A temperature of 73 – 75°F (23 – 24°C) is maintained in the wind tunnel. In order to be able to measure precisely, even in winter outdoor temperatures, the concrete tube of the channel is surrounded by a building and is therefore insulated. Before the air accelerated by the blower reaches the measuring section via a nozzle area of 301 ft2 (28 m²), it must be straightened and smoothed with rectifiers and sieves in order to eliminate disruptive turbulence and eddies. For use as an acoustic channel, in which the wind noises are measured inside and outside the test vehicle, extensive noise insulation measures have been integrated. Even at 87 mph (140 km/h), the air therefore flows through the measuring section in a whisper-quiet manner.
Measuring section: five running belts up to 265 km/h
The centerpiece of the 62-ft-long (19-m) measuring section of the wind tunnel is the approximately 90-ton treadmill-balance system with turntable. The new wind tunnel has a five-belt system to simulate the road: a small treadmill runs under each wheel and a 29.5-ft-long (9-m) and over 3.3-ft-wide (>1-m) center treadmill runs between the wheels. All five belts run synchronously with the wind and thus represent exactly the same conditions as on the road up to 165 mph (265 km/h). The 24-ton scale on which the vehicles are mounted is extremely sensitive and measures to the nearest gram. Even the supply lines of the cables must be laid in such a way to do not introduce any disruptive forces into the system. The values measured with the help of the aerodynamic balance serve as the basis for determining the coefficients for air resistance force, lateral force and lift force per axle as well as pitch, roll and yaw moment.
The traversing system enables the engineers to position various aerodynamic probes or microphones around the measuring object with very high accuracy in order to be able to carry out pressure, acoustic and speed measurements precisely. The system in the Sindelfingen wind tunnel has seven axes and can thus cover a measuring volume of approximately 62 x 46 x 16 ft (19 x 14 x 5 m). The weight of this system is 26 tons, because even at maximum wind speed, the measuring probes must be held exactly and without vibrations in their position.
The centerpiece of the measuring section of the wind tunnel is the approximately 90-ton five-belt system, which perfectly replicates road conditions. Thanks to the integrated turntable with a diameter of approximately 39 ft (12 m), vehicles to be measured can be rotated at any angle and, for example, crosswinds can be simulated realistically.
From 1943 to today: the “Large Wind Tunnel” in Untertürkheim
The “Large Wind Tunnel” of the then Daimler AG in the Stuttgart-Untertürkheim plant was the world’s first to be specially designed to investigate the aerodynamic properties of motor vehicles. Construction work began in 1939, driven by the legendary aerodynamics pioneer Wunibald Kamm. The first documented measurement took place on February 5, 1943. Due to the war, it was not until 1954 that the wind tunnel was the first in the world to be used regularly for measurements on full-scale cars.
Always brought up to the latest technical standards, the wind tunnel in Untertürkheim continues to be indispensable for Mercedes‑Benz development, especially for contamination studies and windshield wiper tests. The aerodynamicists also still test there whether the camouflage of test vehicles is high-speed resistant. Many commercial vehicles from Mercedes‑Benz are also fine-tuned in “Large Wind Tunnel.”
In addition to the aerodynamic work on vehicles, the wind tunnel is sometimes also used for non-automotive tests. Television segments for reports on hurricanes are filmed here, sleds are being optimized for bobsleighing and even ice skaters explore improving their posture. One of the very special challenges was the aerodynamic investigation of the revolutionary tent roof of the Munich Olympic Stadium.
From tropical to arctic: the weather in the climate wind tunnels
Mercedes‑Benz also operates two climate wind tunnels in Sindelfingen that move weather events indoors. The climate wind tunnels allow engineers to optimize newly developed vehicles or components for all weather conditions at an early stage. For subsequent real-world testing on roads in arctic cold and scorching desert heat, only prototypes that have already proven a high degree of maturity under the most adverse climatic influences are now launched.
One of the two climate wind tunnels is designed as a cold channel with a temperature range of -40 – 104°F (-40 – 40°C). In the warm channel, a temperature range of 14 – 140°F (-10 – 60°C) is available. Both channels have an integrated two-axle roller dynamometer and allow speeds of up to 165 mph (265 km/h) – enough reserves to put even sports cars on the test bench.
Modern measuring technology against wind noise and drafts
A special microphone array helps with noise measurement in the acoustic wind tunnel. The extensive measurements in the interior are also referred to as “acoustic holography.” Mercedes‑Benz uses 64 double microphones (hand array) that can locate problem areas in the low-frequency range. Including the devices for the measurements outside, nearly 500 microphones are used.
Flow measuring dummies, artificial heads and near-field microphones are used in aerodynamic and aeroacoustic development. “Tanja” is such a measuring dummy. Mercedes‑Benz uses ‘her’ to analyze drafts in convertibles and roadsters. More than a dozen sensors on the head, neck and arms measure the flow velocities of the airstream in the interior at the front and rear seats.
From a teardrop car to the VISION EQXX
Aerodynamics at Mercedes-Benz: history
- Inspired by aircraft construction: early aerodynamic optimization of cars
- Records in series production: ancestry to the CLA with EQ Technology
- Aero Champions: concept vehicles and technology platforms such as the VISION EQXX
More than 100 years ago, aerodynamics first came into the focus of science, but it was not until after the second oil crisis that it was widely made a high priority in passenger vehicle development.
The first passenger cars were derived from the horsedrawn carriage. Aerodynamic considerations played no major role at that time due to the low possible speeds. Even the first “real” cars of the Mercedes brand from 1901 struggled against the headwind in a jagged manner. For example, the Mercedes Simplex from 1902 had a frontal area of around 3 m², and its Cd value of 1.05 meant the wind encountered almost ten times as much resistance as in a modern passenger car.
Shortly after the First World War, experts began explore the aerodynamics of automobiles. Aircraft designer Eduard Rumpler (1872-1940) presented his teardrop car in 1921, which with its narrow body not only addressed the question of the frontal area (2.4 m²), but with its teardrop shape minimized the turbulence at the front and in the wake. The result looked unusual, but with a Cd value of 0.28 and an air resistance of 0.67 m², it set a clear signal.
Paul Jaray (1889-1974), the other “father of streamlining,” also came from the aviation industry. In 1921, he applied for a patent that still reads like instructions for building a modern car body – “The lower part of the body has the shape of a half-streamlined body and covers the chassis with the wheels, the engine compartment and the passenger compartment. The underside is flat and runs parallel to the floor surface.” For the first time, the wheels were integrated into the body and the fastback design minimized turbulence at the rear. Because conventional drive technology fit under Jaray’s body shape, some car manufacturers built vehicles according to his principle. In 1935, Mercedes-Benz created a correspondingly shaped prototype.
The biggest disadvantage of Jaray’s streamline was the long trailing rear – a “dead” space. The solution was found in the 1930s by Wunibald Kamm (1893-1966), the first professor of automotive engineering at the Technical University of Stuttgart and in 1930, founder of the private non-profit Research Institute for Automotive Engineering and Vehicle Engines Stuttgart (FKFS). Kamm sharply cut off the streamlined rear and developed the prototype of an aerodynamically innovative passenger car with the K-Wagen from 1938 to 1941. The term “Kammback” for the sharp trailing edge is still used today. The K3 car was based on a Mercedes‑Benz 170 V and, with a frontal area of 2.1 m², was characterized by a Cd value of 0.23, which was measured in the model wind tunnel at the time.
Increasing prosperity and falling gasoline prices in the 1950s lessened the focus of aerodynamics in passenger cars. It was not until the second oil crisis in 1979 that renewed attention was placed on minimizing consumption and air resistance in passenger cars. The production cars from Mercedes‑Benz therefore repeatedly set standards in terms of aerodynamics. For example, the S‑Class 126 series presented in 1979 with a Cd of 0.36, the sedans of the E‑Class 124 series introduced in 1984 with a Cd of 0.29 and the S‑Class sedan (W 220) presented in 1998 with a Cd of 0.27. With a Cd of 0.22 and a frontal area of 2.19 m², the CLA Coupe (W 117) achieved the lowest air resistance of all production vehicles worldwide in 2013 (in addition A‑Class sedan in 2018 and the S‑Class 223 series in 2020). Most recently, the EQS reached for this title in 2021. With a Cd value from 0.20, the electric sedan is the most aerodynamic production car in the world.
Ahead of their time: record cars, streamlined cars and concept vehicles
Aerodynamically-perfected racing and record cars also have a long tradition at Mercedes‑Benz. The Mercedes‑Benz W 25 record car of the 1936 season was the first to feature a chassis with a full streamlined body. In the wind tunnel of the Friedrichshafen Zeppelin Works, the experts analyzed and optimized the body in terms of flow technology. The result: a Cd value of 0.24, a speed world record and three international class records. Rudolf Caracciola achieves a top speed of 231.2 mph (372.1 km/h) with the 562-hp record car.
The follow-up project, the Mercedes‑Benz W 125 record car, set the speed world record on public roads on January 28, 1938 – a record that stood for nearly 80 years. Rudolf Caracciola reached a speed of 268.9 mph (432.7 km/h). The record version of the Silver Arrow W 125 was perfectly prepared for its special purpose in the wind tunnel of the German Research Institute for Aviation in Berlin-Adlershof. The flat, fully clad body with a wedge-shaped rear reaches a sensational Cd value of 0.16. This also includes a radically reduced air intake at the front.
The aerodynamic findings were also implemented on road cars. The Mercedes‑Benz 540 K Streamliner built in 1938 crowns the development of aerodynamically optimized Mercedes‑Benz vehicles of the 1930s. With the flowing lines and low silhouette of its aluminum body, the minimized sources of interference on the surface, and the clad underbody, the Streamliner exemplifies the findings of research – it has a remarkably low Cd of 0.36.
The streamline of the Silver Arrows came back into the focus of the public in 1954 with the completely newly developed W 196 R race car. The aerodynamically optimized streamline version was first built for the 1954 season because the opening race in Reims/France allowed very high speeds. A second variant with open wheels followed shortly thereafter. The racing comeback of Mercedes‑Benz ended spectacularly. Juan Manuel Fangio and Karl Kling achieved a double victory. With the improved version of the Streamliner, Fangio also won the 1955 Italian Grand Prix.
From 1969, Mercedes‑Benz built a series of experimental and record vehicles with the internal designation C 111. The C 111-III diesel record car from 1978 was consistently aerodynamically optimized. The vehicle is narrower than its predecessors, has more wheelbase, full fairing of the wheels and a long trailing rear. These measures contributed to a reduced Cd of 0.18. During record runs in Nardò, the Streamliner reached speeds of over 186 mph (300 km/h). The nine world records of the C 111-III also include the one over 1,000 miles (1,609 km) with an average speed of 198 mph (319 km/h).
The Concept IAA (2015) embodies two cars in one: a four-door coupe with a fascinating design and an aerodynamics world record holder with a Cd of 0.19. In addition, from approximately 50 mph (80 km/h), the study automatically switches from design mode to aerodynamics mode and changes its shape through numerous active aerodynamics measures. Eight segments extend from the rear and lengthen it, extendable front flaps in the front bumper improve the flow around the bow and the front wheel arches, the active wheels change concavity, and the fin in the front bumper moves aft to optimize the flow on the underbody.
With a Cd of 0,173, the VISION EQXX (2022) features even less air resistance than an American football. The technology platform owes its outstanding Cd value to the streamlined shape, the innovative, aerodynamically neutral cooling plate in the underbody and the elaborate integration of passive and active aero elements into the body.
As part of the CONCEPT AMG GT XX technology program, research was conducted into a fundamentally new technology – “Aerodynamics by wire”. For the first time, the research team was able to use an electric plasma actuator to create a targeted flow separation on a body curve at the rear. Normally, this requires a physical, geometric spoiler lip on the outside of the vehicle. This highly innovative solution reduces air resistance, improves aero performance and enables completely new design freedom.
1On January 28, 1938, the Mercedes-Benz W 125 record car set a speed world record on public roads with its drag coefficient (Cd value) of 0.17: Rudolf Caracciola reached a speed of 432.7 km/h on the A5 between Darmstadt and Frankfurt.
2The record-breaking C111-III had a drag coefficient of 0.183.
3Cd value determined in the Daimler aeroacoustic wind tunnel at 140 km/h wind speed
SOURCE: Mercedes-Benz
