Concepts · 2005
The car that wanted to be a fish.
Mercedes engineers went looking for the most aerodynamic shape in nature. They found it on a coral reef — and it looked nothing like a teardrop.
Washington, D.C., June 7, 2005. Not a motor show — a science symposium. On the DaimlerChrysler stand sits a rounded, glassy compact car in two-tone green, and beside it, enormous and gently absurd, a model of a tropical fish. The car is the fish.
For the first time, Mercedes said, its engineers had not borrowed a detail from nature — a lotus-effect paint here, a gecko-grip tire there — but a whole animal: shape, structure and all. The donor was the yellow boxfish, Ostracion cubicus, a reef dweller the size of a fist. The result was called, plainly, the Bionic Car.
Chapter I
An unlikely muse.
The boxfish should not work. It is, as the name says, a box — angular, blunt, seemingly the opposite of streamlined. But when the engineers in Stuttgart tested an accurate model of it in their wind tunnel, it returned a drag coefficient of 0.06 — astonishingly close to the 0.04 of the ideal teardrop, from a shape that could also swallow passengers and luggage.
A quarter-scale clay car modeled closely on the fish measured 0.095 — a value then unprecedented in automotive engineering. The brief wrote itself: turn the reef fish into a real, driveable Mercedes.
The fish had a second gift. Its body is armored in hexagonal bony plates that deliver maximum strength for minimal weight. Using computer methods that mimic natural growth — adding material only where stress demands it — the engineers designed body panels the same way. The Bionic’s door panels came out 40 percent more rigid than conventional ones; a whole body built on the principle, they calculated, would weigh a third less with undiminished crash strength.
The finished concept was a compact one-box four-seater, 4.24 meters long, with a full glass canopy — and a drag coefficient of 0.19, better than any production car of its day.
- Drag coefficient
- 0.19
- Power
- 140 PS
- Consumption
- 4.3 ℓ
- NOx emissions
- −80%
Chapter II
Seventy miles to the gallon.
Under the sloping hood sat a 103 kW turbodiesel — 140 PS moving a car so slippery it averaged 4.3 liters per 100 km, around 70 miles per gallon. Held at a steady 90 km/h, consumption fell to 2.8 liters per 100 km — 84 mpg from a four-seater with luggage space.
The Bionic’s other premiere hid in the exhaust: selective catalytic reduction, injecting a urea solution to cut nitrogen-oxide emissions by up to 80 percent. The technology the fish-car introduced went into production the following year as BLUETEC — and ended up in millions of Mercedes diesels.
Epilogue
The fish that lied.
The Bionic never became a product — DaimlerChrysler said so from day one — but its exhaust technology shipped almost immediately, and its obsession with efficiency by shape echoed for decades: the production Mercedes with the world’s lowest drag figures, from the 2013 CLA to the EQS, are its descendants in spirit.
The muse fared less well. In 2015, researchers writing in the Journal of the Royal Society Interface re-tested the boxfish and found its drag-reduction performance “relatively low” compared with ordinary fish shapes — the reef legend was partly a myth. The car, though, had measured 0.19 in a real wind tunnel. Whatever the fish’s secret was, the Bionic kept its half of the bargain.