As emissions standards get tougher, manufacturers are being forced to think outside the box in the quest for better fuel economy. One of the obvious areas to focus on is aerodynamics, where small tweaks can lead to big fuel savings. Shape-shifting designs represent one of the more radical approaches in this area, and Mercedes has taken this to another level with its Concept IAA (Intelligent Aerodynamic Automobile), which changes shape at higher speeds to cut through the air more efficiently.
With its teardrop shape and sleek styling, the Concept IAA – which, appropriately enough, debuted at IAA in Frankfurt – doesn't look all that different to the autonomous F 015 concept unveiled earlier this year – it's only once the car gets going that Mercedes' latest concept sets itself apart.
When the car hits 80 km/h (50 mph), a series of shape-changing alterations take place; eight segments built into the rear of the car extend the tail section by up to 390 mm (15 inches) for a more streamlined profile, while flaps in the front bumper extend by 25 mm (0.98 inches) forwards and 20 mm (0.79 inches) towards the rear of the car, improving airflow around the front wheel arches.
Beyond the front and rear bumpers, the rims go from having a 55 mm (2.17 inch) dish to completely flat, and the louver built into the front bumper moves backwards by 60 mm (2.37 in). So, what does that all mean? Basically, by moving these different parts, Mercedes is able to bring the drag coefficient down from 0.25 to just 0.19. To put that in perspective, Mercedes' own CLA Coupe only manages a drag coefficient of 0.23, as does the bigger Audi A4 with its flat underbody and carefully shaped suspension components.
Mercedes hasn't quoted fuel economy numbers for the Concept IAA, but with its aero add-ons extended the company says the car emits 3 g/km less CO2 and is able to eke an extra 4 km (2.49 mi) of all-electric range out of its hybrid powertrain.
It's also worth keeping in mind that the benefits of the vehicle's shape-shifting aerodynamics are more dramatic at highway speeds than they are in the low-speed, urban areas that receive a two-thirds weighting in the New European Driving Cycle (NEDC) emissions testing.
As well as offering up a high-tech take on aerodynamics, the Concept IAA previews some of the tech that will feature on next year's E-Class, including a Car-to-X networking system that allows cars to wirelessly warn each other about accidents or potential hazards further along the road.
From the front, the Concept IAA's nose looks like an elongated version of the face on the F015, with horizontal louvers and integrated headlights, while the elongated profile and sharp rear end are exaggerated with the rear-aero section extended. Inside, the concept follows the design line of the S-Class and S-Class Coupé, with the addition of Optical Finger Navigation touchpads on the steering wheel to allow drivers to scroll through menus on the instrument binnacle.