Mercedes-Benz is a global brand, no matter where in the world you travel, no matter how remote, there is a good chance you’ll see a Mercedes on the street or off-road.  But different parts of the world call for different vehicle features,  Some Mercedes need to handle heat, like the 130 degree  Death Valley temperatures we saw this week, or freezing cold temperatures of -40 degrees that are like those experienced in Norwegian winters and some need to stay dry in some of the wettest places on earth.  But Mercedes doesn’t make a vehicle specific to each climate, so how do they do it?

Watch the video below to see how a Mercedes car is designed and tested to ensure that each and every model can handle the demands of not just one climate but all.

Heat: The test bench of the heat tunnel features an array of 32 lamps designed to simulate the sun’s powerful rays by generating up to 1200 watts per square metre over an area measuring 8 x 2.5 metres. In extreme cases, the tunnel can reach temperatures of up to 60 degrees Celsius – as hot as Death Valley or the Sahara. With the infinitely variable “hot road” function, it is even possible to reproduce the effect of warm asphalt on a summer road.

Rain: The development engineers can arrange for up to 2400 litres of water per hour to pour down on a vehicle. But it’s not just the volume of rain that can be varied – the size of the drops can also be pre-set. A simulated tropical storm can be used to check whether a car is watertight overall and whether the windscreen wipers are functioning properly.

Cold: The cold tunnel can generate temperatures down to minus 40 degrees Celsius, for example, to test a vehicle’s heating system. As soon as the thermometer drops below freezing, the facility switches to “cold lighting” as conventional neon lamps cannot withstand frost. At temperatures below freezing, the pre-cooled spray water turns into snow and the metal floor becomes as slippery as an ice rink.

Wind: The huge fan is capable of simulating winds speeds of up to 265 km/h. Even at a wind speed of 100 km/h you are no longer able to stand upright. The fan is mounted on massive steel springs to protect the facility’s electronics from the slightest vibration.

Earlier in the week we began taking a look at the achievements Mercedes-Benz has made in vehicle aerodynamics, in the even that you missed it, click here to read the previous article or read on for Part 2 of our Mercedes-Benz Aerodynamics series.

For almost three decades, the aerodynamic specialists at Mercedes-Benz have been breaking one record after another. At present the brand’s models occupy the top position for aerodynamics in practically every vehicle segment. In its BlueEFFICIENCY Edition, the new CLA-Class has even established a new world record with a Cd figure of 0.22 and wind resistance x A of 0.49 sq. m. Highly sophisticated improvements to both the overall vehicle and detailed features contribute to this good performance. The coming new S-Class will likewise be at the top of its segment for aerodynamic efficiency. Mercedes-Benz models also take the lead in almost all vehicle classes where aeroacoustics are concerned.

1984 saw the debut of cable TV in Germany, the West runway at Frankfurt airport was taken into operation and the Olympic Games were held in Los Angeles. In the same year the W124-series E-Class scored an aerodynamic triumph with a Cd figure of 0.29. It was the first series production saloon to achieve a Cd figure below 0.30, setting a standard by which all saloon cars are judged to this day – and which by no means all can equal.

Since then Mercedes-Benz has established one aerodynamic world record after another – across all vehicle classes and body configurations. The following factors are the secret behind this continued leadership:

• Good basic dimensional concept and optimised external shape
• Aerodynamically optimised underbody with extensive engine compartment and underbody panelling
• Large area of cladding on the rear axle
• Aerodynamically optimised rear silencer followed by a diffuser
• Wheel arches with optimised spoilers and other features such as slits
• Large front wheel overhangs with optimised airflow onto and over the front wheel arches
• Aerodynamically efficient design of the front and rear aprons and the rear roof edge
• Hub covers or specially developed aero light-alloy wheels with low air resistance
• Aerodynamically optimised exterior mirror housings
• Low A-pillar shoulder with adapted A-pillar geometry
• Spoiler lip on each tail light
• Improved sealing of the radiator section and airflow guidance to make efficient use of the available cooling air
• Use of a cooling air metering system (adjustable louvre)

Sealed headlamp surrounds

One very recent underbody feature is the patented wheel spoiler already mentioned, which was developed with the help of airflow analysis. This seemingly innocuous component reduces undesirable air turbulence in the wheel arches in no less than three ways, by lowering linear turbulence, deflecting the airflow from the wheels and stabilising shear waves with its serrated edge. The wheel spoiler remains effective whatever the suspension level and wheel dimensions.

It was first employed for the B-Class (2011), which with its help achieved a new top Cd figure of 0.26 for series production cars with an enclosed rear. Tail-end turbulence is also considerably reduced. With a basic shape defined according to aerodynamic aspects, the large roof spoiler acts as an airflow breakaway, as do the tail lights. A total of 278,000 CPU-hours of computer time and 1100 hours in the wind tunnel went into the aerodynamic optimisation of the B-Class.

The patented wheel spoiler is also used in the CLA-Class (2013), which has the lowest of all Cd figures at 0.23 – both within the Mercedes-Benz model portfolio and amongst all series production cars. The CLA 180 BlueEFFICIENCY Edition, which is due to be launched in June, will even better this benchmark with a Cd figure of 0.22.

When it comes to compact cars like the new A-Class (2012, Cd = 0.26), coupés such as the E-Class Coupé (2010, Cd = 0.24), saloons such as the E-Class (2009, Cd = 0.25), sports cars like the SL (2012, Cd = 0.27) and SUVs like the M-Class (2011, Cd = 0.32), vehicles in these segments have never before achieved such low Cd figures. The new S-Class is set to continue this trend.

An overview of the key aerodynamic figures for the entire Mercedes-Benz passenger car range:

BEE = BlueEFFICIENCY Edition model, 1 Saloon/Coupé/Estate, 2 Saloon/ Coupé/Estate/Cabriolet, 3 Coupé/Shooting Brake, 4 Coupé/Roadster

More driving comfort thanks to less wind noise: aeroacoustics

Models from Mercedes-Benz also take the lead in almost all segments when it comes to aeroacoustics. The new CLA will have the lowest level of wind noise in its segment. Numerous measures contribute to this peak position:

• Frameless doors with a multi-stage sealing concept
• The high insulating effect of the side windows
• Stemmed exterior mirrors with an optimised shapefamiliar from the C, E and S-Class

Exterior noise is also minimised by the reduced height of the A-pillar shoulder.

Thanks to its acoustic soft top fitted as standard, when closed the E-Class Cabriolet has one of the quietest interiors in the segment for four-seater premium convertibles with a fabric roof. The soft top’s exceptionally high-quality insulation brings about a clearly noticeable reduction in the interior noise level compared to conventional fabric soft tops. Exterior noise from other vehicles, as well as wind noise, is more efficiently absorbed.

Contribution to active safety: anti-soiling measures

Anti-soiling measures are another aerodynamic discipline – and another area in which aerodynamic specialists at Mercedes-Benz have led the field for many years. Soiling can arise from rain, vehicles travelling ahead and spray thrown up by the vehicle’s own wheels. Keeping windows and exterior mirror lenses as clean as possible, and therefore having the best possible visibility under all conditions, makes a contribution to active safety.

In the wind tunnel the aerodynamic specialists optimise components with the help of a fluorescent liquid which makes the soiling clearly visible. The aim is to direct water away so that the side windows and exterior mirror lenses remain clean. This is influenced by the geometry of the A-pillar with its integral components and the geometry of the exterior mirrors and window frames, or trim strips in the case of frameless doors.

Using the side window as an example, minor geometrical modifications to the mirror housing and detailed refinements using seals and a special water-retaining strip enable soiling to be considerably reduced. The standard at Mercedes-Benz is that in the so-called core visibility area, no spray, no trickles and only individual water drops must appear on the mirror lens.

For the last few years, Mercedes-Benz has lead the way in vehicle aerodynamics, whether it be minimizing wind resistance, reducing noise levels, increasing open-top driving comfort and anti-soiling measures, the models from Mercedes-Benz are without question aerodynamically superior to their competition. Mercedes previously relied on the University of Stuttgart and its original wind tunnerl, but now with the new aeroacoustics wind tunnel at the development center in Sindelfingen, the company is also taking the lead in aerodynamic testing.

Before reading on, in order to enjoy this series of articles, here’s a quick overview of what a Cd figure is and how Mercedes-Benz stacks up against others.

The Cd figure is the measure of the aerodynamic efficiency of a solid body, in this case, a car. When a car’s speed increases, wind resistance becomes an increasing factor, adding to the total resistance against the car.  In direct terms, if the Cd figure can be reduced by ten thousandths, fuel consumption falls on average by one tenth of a litre.  The Mercedes-Benz CLA has the lowest of all Cd figures of all at 0.23 – both within the Mercedes-Benz model portfolio and amongst all series production cars. The CLA 180 BlueEFFICIENCY Edition even betters this benchmark with a Cd figure of 0.22.  Compare this to the the Toyota Prius which is rated at 0.25 Cd and the BMW 320d at 0.26 Cd and you see why the CLA’s numbers are so impressive.

Mercedes-Benz CLA

For almost three decades, aerodynamic specialists at Mercedes-Benz have been breaking one record after another. “At present the brand’s models occupy the top position for aerodynamics in practically every vehicle segment”, says Prof. Dr. Thomas Weber, who is responsible for Group Research and Mercedes-Benz Cars Development. In its BlueEFFICIENCY Edition, the new CLA-Class has even established a new world record with a Cd figure of 0.22 and wind resistance x A of 0.49 sq. m. Weber: “This means that the CLA-Class is more streamlined than any other vehicle. Maintaining aerodynamic leadership is a major component of our MBC 2020 product strategy, which we are following systematically for all new vehicle models.”

When it comes to compact cars like the new A-Class (2012, Cd = 0.26), coupés such as the E-Class Coupé (2010, Cd = 0.24), saloons such as the E-Class (2009, Cd = 0.25), sports cars like the SL (2012, Cd = 0.27) and SUVs like the M-Class (2011, Cd = 0.32), vehicles in these segments have never before achieved such low Cd figures. The new S-Class is set to continue this trend.

The SL achieves a Cd figure of 0.27

“Highly sophisticated improvements to both the overall vehicle and detailed features contribute to this good performance,” says Dr. Teddy Woll, Head of aerodynamics/wind tunnels. Emotion meets efficiency: the more aerodynamically efficient a vehicle is, the lower its fuel consumption. Woll: “In the New European Driving Cycle (NEDC), improving the Cd figure by 0.01 already lowers CO2 emissions per km by one gram, by two grams as a function of mean on-the-road consumption, and at 150 km/h by no less than five grams of CO2 per kilometre.” Moreover, safety, comfort and the environment also benefit from the elimination of air turbulence. Because low levels of lift ensure good roadholding, while low wind noise is welcome to both passengers and pedestrians.

Models from Mercedes-Benz also take the lead in almost all segments when it comes to aeroacoustics. The new CLA will have the lowest level of wind noise in its segment.

The blower of the new aeroacoustics wind tunnel has a diameter of nine metres and has 18 vanes that set the air in motion. The maximum wind speed is 265 km/h.

New aeroacoustics wind tunnel: measurements up to 265 km/h

With the “large wind tunnel” in Stuttgart-Untertürkheim, Mercedes-Benz was the first automobile manufacturer to possess a wind tunnel – the first documented measurement was carried out there exactly 70 years ago, on 5 February 1943. With the new aeroacoustic wind tunnel at the development centre in Sindelfingen, the company has once again placed itself at the forefront of aerodynamic testing. The new wind tunnel, which will be taken into operation in mid-2013, follows the Göttingen design. This means that after the measuring stretch the air is directed back to the blower and again accelerated to up to 265 km/h. Before the air accelerated by the blower reaches the measuring stretch via a nozzle system covering 28 sq. m., it must be directed and smoothed to eliminate unwanted turbulence and eddies. This done using rectifiers and sieves. Extensive noise insulation measures are integrated to allow use as an acoustic tunnel where interior and exterior wind noise can be measured for the relevant test vehicle. Even at 140 km/h the air flowing through the measuring stretch is therefore as quiet as a whisper.

Aerodynamic optimisation, taking the Mercedes-Benz CLA 180 BlueEFFICIENCY Edition as an example

The centrepiece of the 19-metre long measuring stretch in the wind tunnel is the roughly 90-tonne conveyor belt/balance system with a turntable. The new wind tunnel has a 5-belt system to simulate the road. The conveyor belt/balance system is integrated into a turntable with a diameter of twelve metres. This means that the vehicles to be measured can also be subjected to an angled airstream to simulate cross-winds. The traversing system enables the engineers to position various aerodynamic sensors and microphones around the test vehicle with very high precision.

With its 360° screen, fast electric power system and the twelve-metre-long rail for transverse or longitudinal movements, the new “Moving Base” simulator from Mercedes-Benz is the most powerful in the entire car industry. It went into operation at the end of 2010.

“With the simulator, we are able to realistically reproduce highly dynamic driving manoeuvres such as lane-changing and therefore research the behaviour of the driver and the vehicle in road traffic in great depth,” explains Prof. Dr. Thomas Weber, Member of the Daimler Board of Management responsible for Group Research and Head of Mercedes-Benz Cars Development. The system is not intended to replace real test drives entirely. The simulator will enable systems and components for future Mercedes models to be tested throughout all development phases, however.

The driving simulator is furthermore used to conduct trials with test subjects. During these, normal car drivers are able to approach the physical limits of driving performance with absolutely no danger, providing the Mercedes engineers with invaluable findings on the acceptance and operation of new safety systems.

How the simulator works

The simulator cell is basically a cab fixed to a hexapod on six moveable supports. Inside there is a complete Mercedes model in which the test driver is seated, as well as the 360° projection screen showing a realistic image of the traffic scenario, with moving pedestrians, oncoming traffic and houses.

The vehicle controls are linked to the computerised control system of the driving simulator by data lines. When the test driver turns the steering wheel, accelerates or operates the brakes, these reactions are registered by the computer control system and have the same effects as in real traffic situations. The scenery on the screen changes constantly, while the hexapod and the linear movements combine together to create a realistic impression of vehicle motion. The computer calculates the driving behaviour of the car more than 1000 times per second, issuing the relevant commands to the electrics. It is able to move the cell transversely by up to twelve metres at a maximum speed of ten metres per second (36 km/h), so that double lane-changes can also be simulated, for example.

Equally high-tech: part of the energy required to operate the simulator is recovered by means of energy recuperation during braking and fed into the power network of the Sindelfingen plant.

In its role as a safety pioneer, Mercedes-Benz has long led the way in the use of simulators, too. The first driving simulator, an in-house development, was commissioned at the Daimler-Benz research centre in Berlin-Marienfelde over 25 years ago.

Have you ever considered the possibility that on those 100 degree days when you are stuck in traffic that your car might overheat or when you’re in a -20 degree blizzard that your car might also run into trouble?  Luckily, if you’re driving a Mercedes, you don’t have to worry about such trivial things like weather. Mercedes’ new testing facility at the Sindelfingen site is specifically designed to run prototypes through a myriad of weather conditions.  

Mercedes-Benz recently inaugurated two wind tunnels capable of temperatures ranging from -40 degrees up to 140 degrees Fahrenheit.  In addition to testing the Mercedes-Benz Prototypes against brutal temps, the test vehicles can also be hit with hurricane force winds up to 164 mph, heavy rains and snow.

The ability to run the prototype vehicles through at such an early stage allows Mercedes-Benz to move more quickly through the design and development process, only have to do real life road tests on components that have already proven themselves.  Another advantage of the new climatic wind tunnels is that they are designed to accommodate the use of hydrogen and therefore eminently suitable for all alternative drive systems of the future. Special sensors and an effective air extraction system mean that fuel-cell powered vehicles can also be subjected to exacting test programmes here.

Expand the full press release or view the photo gallery below to find out more.