Mercedes fishes for inspiration

Mercedes has unveiled a biomimetic concept car which has a tropical fish to thank for its unusual shape.

Engineers at Mercedes-Benz used the aerodynamic properties of the boxfish to design the ‘bionic car’.

The body of a boxfish is extremely streamlined, despite its boxy, cube-like shape. Using this as a starting-point, the engineers created a 1:4 clay model of the car.

During wind-tunnel testing the model had a drag coefficient of just 0.095, which is the lowest ever measured in automotive engineering.

The full-sized concept car is one of the most aerodynamically efficient in its size category, with a drag coefficient of just 0.19 — around half the drag of a Mercedes 300SE.

The car is 4.24m long with room for four occupants plus luggage.

The boxfish also inspired the car’s body construction. The external door panelling is based on the fish’s lightweight but sturdy outer body, which consists of many hexagonal, bony plates. The resulting car panel is up to 40 per cent more rigid than conventional designs, but far lighter. Mercedes claims that the vehicle’s total weight will be reduced by around one third without the car’s strength or safety being affected.

The car uses selective catalytic reduction (SCR) technology to reduce exhaust emissions. DaimlerChrysler is testing SCR technology worldwide, which allows diesel engines to run at high temperatures, improving fuel economy and minimising nitrogen oxide emissions.

The concept car’s fuel consumption is 4.3 litres per 100km in the EU driving cycle (the standard measure of fuel consumption) — 20 per cent less than a comparable seriesproduction car.

The car uses an operating fluid called ‘AdBlue’ as an exhaust treatment system, which reduces the vehicle’s nitrogen oxide emissions by up to 80 per cent, Mercedes claims. AdBlue is sprayed into the exhaust in precise quantities and converts harmful nitrogen oxides into nitrogen and water. The fluid is stored in the spare wheel recess and the amount stored is calculated so that the driver need not worry about replacing it until the car is serviced.