Mercedes-Benz has lifted the covers off its shapely Concept IAA showstopper the evening before the Frankfurt Motor Show, revealing a sleek four-door form powered by petrol and electricity that is expected to preview the next-genearation CLS.
But though it may herald the impending arrival of the next production CLS, one feature of the Concept IAA that will probably remain on the Frankfurt stand will be its shape-shifting active aero bodywork.
Above speeds of 80km/h, the Concept IAA's front splitter and front cheek vents retract to reduce drag, while the tail of the car extends to further streamline its shape.
Even the wheel spokes transform into a flatter shape to smooth out airflow over the wheel wells, a common source of drag-generating turbulence on a car.
All up, the IAA's contortion act results in a slippery coefficient of drag of just 0.19 - and adds 390mm to its considerable 5040mm length.
To put that in perspective, the IAA's Cd in non-aero mode is a still-respectable 0.25 - slightly more than a Tesla Model S.
Powered by a 205kW 2.0 litre turbocharged petrol engine and electric motor combo, the Concept IAA can cruise for on electric power alone for up to 66km, and boasts a combined cycle fuel economy of 1.47 l/100km. Keep it charged from a wall outlet and that figure can drop to zero.
The Concept IAA's interior is also a preview of things to come, with touch-sensitive controls integrated into the steering wheel that alter the 'pages' displayed by the reconfigurable instrument panel.
A double-bubble all-glass roof covers the concept's four seats, with the rear passengers enjoying their own individual bucket seats.