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Aerodynamic optimizations include windows that fit flush on the outside, a blue LED touchpad instead of door handles, and lowering of the chassis, resulting in a ground clearance of 100 mm (3.9 in).

Mercedes' concept stresses connectivity, record-breaking aerodynamics

Among its five world premieres at the IAA (Frankfurt Motor Show) 2015, Mercedes-Benz surprised show-goers with the Concept Intelligent Aerodynamic Automobile (Concept IAA), which the German automaker also calls the “Digital Transformer.” The concept car is designed to show how far advanced Mercedes-Benz already is in the “digitalization” of automotive development and production, according to Dr. Dieter Zetsche, Chairman of the Board of Management of Daimler AG and Head of Mercedes-Benz Cars.

“The Concept IAA shows that the real and the virtual world are merging more and more at Mercedes-Benz,” said Zetsche, speaking at the concept's Frankfurt Motor Show reveal. “Never before have we developed a vehicle concept as quickly as our Concept IAA. What previously took up to one and a half years, we managed in less than 10 months thanks to digitalization.”

The four-door "coupe" is 5040 mm (198.4 in) long—5430 mm (213.8 in) long when in “aerodynamic mode” (see below)—1995 mm (78.5 in) wide, and 1305 mm (51.4 in) high. Its wheelbase measures 2975 mm (117.1 in), and the front/rear track widths are 1710 and 1770 mm (67.3 and 69.7 in), respectively.

A gasoline/electric plug-in hybrid drive with a total output of 205 kW (275 hp) provides the concept car with an electronically limited top speed of 250 km/h (155 mph). In aero mode, the vehicle manages an all-electric range of 66 km (41 mi) and emits 28 g/km of CO2. In shorter “design mode,” the range is 62 km (38 mi) and CO2 emissions are 31 g/km.

Active aerodynamics

The Concept IAA is a world record-breaker for aerodynamics for a four-door four-seater, according to Mercedes, with a Cd figure of 0.19. At around 80 km/h (50 mph), the vehicle automatically switches from design mode to aerodynamic mode, changing its form with a number of active aerodynamic features.

At the rear end, eight segments made of carbon-fiber-reinforced plastic (CFRP) deploy to extend its length by up to 390 mm (15.4 in), “substantially” reducing the after-flow zone behind the vehicle and thus drag. Flaps in the front bumper extend outward by 25 mm (1.0 in) and rearward by 200 mm (7.9 in), improving airflow around the front end and the front wheel arches. The fin in the front bumper retracts by 60 mm (2.4 in) to improve flow along the underbody. In addition, active wheel rims change their cupping from 50 mm (2.0 in) to zero—from five-spoke to flat-disc wheels.

As a result of this transformation, the Cd value improves from 0.25 to 0.19. The frontal area totals 2.16 m² (23.3 ft²). Because the downward slope of the concept car’s roofline begins further toward the front, designers incorporated two “rises” over the rear seats to offer the rear passengers sufficient headroom.

Other aerodynamic optimizations include windows that fit flush on the outside, a blue LED touchpad instead of door handles, and lowering of the chassis, resulting in a ground clearance of 100 mm (3.9 in). The underbody paneling partially covers the center tunnel, with perforations to allow cooling of the exhaust system, and extensive cladding on the rear axle. Cameras in the side air outlets behind the front wheel arches project images onto the split-screen rearview mirror in the interior, making exterior mirrors unnecessary.

As on the new C-Class, an adjustable radiator grille shutter (air panel) helps to reduce drag. When only low cooling requirements apply, the concentric louvers in the radiator grille are closed to prevent air from entering into the engine compartment. Basic ventilation then occurs primarily via the Mercedes star and the cooling air opening in the bumper.

The aerodynamic features were developed with the aid of numerical flow simulation. The automaker’s aerodynamics experts used around one million CPU hours to simulate the airflow, working through around 300 variants. The work involved is roughly equivalent to that required to develop a production model, according to Mercedes. Fine-tuning then took place in the wind tunnel in Sindelfingen.

“The Concept IAA applies intelligent innovations to resolve the conflicting aims of functionality and aesthetics and shows that we still have plenty of ideas on how to achieve further improvements in efficiency,” said Prof. Dr Thomas Weber, Member of the Daimler Board of Management responsible for Group Research and Head of Mercedes-Benz Cars Development.

Digitalization and connectivity

In addition to impressive aerodynamics, the Concept IAA reflects the “fundamental technological changes” taking place in the automotive industry, for which the primary driving force is "digitalization, also known as Industry 4.0." According to Zetsche, a continuous digital process chain from research and development through production to marketing and sales, logistics, and service is already becoming a reality at Mercedes-Benz.

The design and aerodynamic shaping of the concept was aided by the digital networking of different specialist departments. Designers employed the latest algorithmic design methods to handle the complex geometries, which were turned into reality via production technologies such as rapid prototyping.

The concept car also is equipped with a large number of sensors and modules that enables autonomous driving and car-to-x communication. Inside, the Concept IAA continues the design theme of the S-Class and S-Class Coupe. New touch-based functions hint at what the interior of a business saloon might look like in the near future, Mercedes says.

The automaker worked with Silicon Valley-based Nvidia and The Foundry, a creative-software developer for visual effects and games, on the in-vehicle digital displays.

The instrument cluster consists of two 12.3-in screens positioned side by side. The displays are flush-mounted behind glass. The glass elements are all bonded, which involves filling the minimal gap between front glass and film with a transparent adhesive in the production process. This provides for substantially improved optical quality and robust screens, according to Mercedes.

The center console features a trim element of curved glass in which a touch display is integrated. This is where air-conditioning and seat-adjustment functions are operated, and where entry buttons for the different operating menus are located. The exterior aerodynamic elements can be controlled in a new menu.

The two-spoke steering wheel also incorporates touch-based operating functions: OFN (Optical Finger Navigation) buttons, embedded in the clusters in a similar hovering manner as the touchpad in the center console, allow the driver to scroll through the instrument cluster menus. The OFN button on the left controls the left-hand display, the button on the right controls the right-hand display.

Trim elements are all-aluminum, and the entire floor of the show car is covered in leather. The eight air vents have been produced by Swarovski, accented by blue and red ambient lighting.

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