History · 1969–1993
Not a Mercedes-Benz.
Gullwing doors, a hand-built V8 behind the seats and a three-pointed star bolted into the nose. Stuttgart's position, in writing, is that this car has nothing to do with it.
In 1978 a pearl-white wedge with gullwing doors and a three-pointed star screwed into its nose began turning up in the German motoring press. No Mercedes-Benz designer had drawn it, no Mercedes-Benz factory had built it, and no Mercedes-Benz board had ever approved it.
It had been designed in a Porsche engineer's spare time and assembled in a Frankfurt tuning shop, and measured against the mid-engined supercars it was aimed at, it was very nearly right. Mercedes could have stopped it with one telephone call. Instead the company stayed quiet until the photographs were everywhere — and then stayed quiet for another forty years.
Chapter I · 1969–1977
A car as a job application
Eberhard Schulz did not apply to Porsche with a portfolio. He built a car in the garage at home — a low mid-engined coupé he called the Erator GTE — and drove it to Zuffenhausen, and to Untertürkheim as well. Porsche's design department hired him in 1970.
The years that followed he spent on the 911. But the car he wanted to build was somebody else's: a successor to the 300 SL Gullwing, which Mercedes had stopped making in 1963 and shown no interest in replacing. From about 1972 he drew it in his own time, and he took the shape from the mid-engined machines Mercedes was still building — the C111 research cars, orange, wedge-shaped and unobtainable.
The result was not a homage in the polite modern sense. It took what it wanted from the 300 SL — the doors, the side exhausts, the vents — then put a V8 behind the seats and wrapped the lot in the flattest body he could make work.
It was also, for one man with a drawing and a day job, unbuildable. What he needed was a workshop that welded spaceframes and answered to nobody.
Chapter II · 1978
The wedge that came out of a tuning shop
In 1978 Schulz left Porsche for b+b, Rainer Buchmann's tuning house in Frankfurt, which had made its name on lavishly modified Mercedes and Porsches and had exactly the workshop the drawing needed.
What they built was a tubular steel spaceframe under a glassfibre body, with independent suspension and discs at all four corners; the steering came from a Porsche 911 and the suspension layout from the 928, a car Porsche had only just launched. Behind the seats sat the M100 — the hand-built V8 from the 600, the engine AMG had already made famous by boring it out for racing — tuned, Schulz said later, to as near 400 hp as the era allowed.
Which displacement it actually was is still argued over: the 6.3 as Mercedes built it, AMG's 6.8, or the 6.9 from the big S-Class. What nobody disputes is what happened next. The body went into a wind tunnel and came back with a drag coefficient of 0.311, which gave the car its name — CW311 — and which also, conveniently, saluted the C111 that had started the whole thing.
The details were the kind a small team can afford and a big company cannot. There were no exterior mirrors at all: a periscope stood up out of the roof and fed the view back to the driver. The paint was pearlescent white, still exotic in 1978. The finished car stood 1.11 m tall and weighed 1,250 kg, and period figures claim 319 km/h — a number nobody has ever independently checked.
- Drag coefficient
- 0.311
- Power, as quoted
- 375 PS
- Curb weight
- 1,250 kg
- Overall height
- 1.11 m
The number that named the car
cW 0.311
Measured in the wind tunnel in 1978 — and from then on, the car's name.
The badge
Fitted without asking.
A full-size three-pointed star went into the nose panel before the car was ever shown in public. Mercedes knew roughly what was being built in Frankfurt and did not intervene, and the story ever since has been that the factory then let the badge stay, on the condition that exactly one car would wear it. Nobody has produced the letter. What is on the record is the company's position today, and it could not be blunter.
“The CW 311 was not made by Mercedes-Benz and is — due to that fact — no Mercedes-Benz. The three-pointed star was put on the car without permission. Eberhard Schulz never worked for Daimler, the CW311 is not on display in the Mercedes-Benz Museum and our archives have no documents or pictures of the car.”
Chapter III · 1978–1982
Die Bombe
A German magazine called it die Bombe, which was roughly the reception everywhere. It went up on bedroom walls, and in 1980 it took a starring role in Car-napping, a German comedy about stolen cars, which did the legend no harm whatsoever.
Why Stuttgart tolerated the star has never been properly explained. 1978 was also the year BMW launched the M1, the mid-engined car Munich actually did build, and one long-standing theory holds that Mercedes was content to let a pearl-white wedge wearing its badge take a share of the coverage. It is a theory and nothing more.
What the car never got was a production line. Mercedes had no interest in building it, and asking a company that had spent the decade perfecting the S-Class to add a mid-engined two-seater was never a realistic proposition. The demand from people who wanted one was real, though — and it went unanswered for six years.
Schulz and Buchmann fell out in 1982 and parted badly. The design left with Schulz; b+b was bankrupt within a year. In Leonberg, west of Stuttgart, Schulz registered a company of his own and gave it a name that was really an acronym: Isdera, for Ingenieurbüro für Styling, Design und Racing.
Chapter IV · 1982–1993
Thirty cars and one telephone number
Isdera's first product was not the wedge. It was the Spyder, a small mid-engined two-seater shown in 1982 with a modified Mercedes four-cylinder making 185 PS; a 3.0-liter six followed in 1987, at which point the cars became the Spyder 033i and 036i.
The CW311 itself reached production in 1984, presented at Geneva as the Isdera Imperator 108i. The wheelbase had grown by 80 mm and the car had been made properly usable, but the body was recognizably the one from 1978. Where the Mercedes star had been there was now an Isdera badge. The periscope stayed.
The hardware stayed Mercedes: a 5.0-liter M117 V8 with 300 hp to begin with, then 5.6 liters, and finally 5.6- and 6.0-liter AMG versions beyond 400 hp, all driving through a five-speed ZF manual. A 1991 facelift improved the cooling and revised the exhaust.
There was no showroom, no dealer network and no brochure worth the name. If you wanted an Imperator you telephoned Schulz, agreed a specification and paid before a panel was laid up, and a handful of craftsmen built your car. Thirty were finished before production stopped in 1993.
- Imperators built
- 30
- Largest engine
- 6.0 L V8
- Gears
- 5
- Exterior mirrors
- 0
Chapter V · 1993
Commendatore
The successor appeared at the Frankfurt show in 1993, named after Enzo Ferrari in a gesture nobody could miss: the Isdera Commendatore 112i. It had two pairs of gullwing doors, a flat underbody, an air brake that stood up under braking, a chassis that lowered itself as speed rose, and a 6.0-liter Mercedes M120 V12 with 408 PS. Its drag coefficient, measured this time in Mercedes' own wind tunnel, was 0.306.
It was not a running car when it was shown. Development had reportedly cost four million euros, the money behind it was Japanese, and the bubble had burst: Isdera was insolvent within months of its own debut. Swiss investors bought the company, and Schulz finished the car so that it could at least be driven.
In 1999 the new management put it back on a Frankfurt stand as the Silver Arrow C112i — conventional mirrors in place of the periscope, a 6.9-liter V12 with 619 PS and, remarkably, Mercedes-Benz badges and no Isdera badging at all. Twenty-one years after the CW311, the same trick played the other way round.
Exactly one Commendatore was ever built. Isdera bought it back in 2016 and restored it to 1993 specification, and in February 2021 it sold at auction in Paris for €1,113,125.
Twenty-four years.
From a car built to get a job, to a marque with thirty cars to its name and a badge it was never granted.
1969
The job application
Schulz builds the Erator GTE in the garage at home and drives it to Stuttgart. Porsche hires him in 1970.
1972
A successor on paper
In his own time he starts drawing a mid-engined heir to the 300 SL, modeled on the C111 research cars.
1978
CW311
Built at b+b in Frankfurt around an AMG-tuned M100 V8. The wind tunnel returns 0.311, and names it.
1982
Isdera
Schulz leaves b+b, takes the design with him and founds his own company in Leonberg.
1984
Imperator 108i
The CW311 finally reaches production at Geneva, 80 mm longer in the wheelbase. Thirty are built.
1993
Commendatore 112i
A 408 PS V12 successor with a cW of 0.306. One is finished before the money runs out.
Epilogue
The car that isn't there
Mercedes did build a mid-engined supercar of its own eventually. The C112 was shown in 1991, took some seven hundred orders and was canceled regardless; the CLK GTR Straßenversion of 1998 was the first mid-engined Mercedes-Benz anyone outside the company could actually buy — twenty years after a Porsche engineer's spare-time drawing had done much the same job in a Frankfurt workshop.
Which leaves the CW311 in a strange position. It is the most convincing Mercedes-Benz supercar of the 1970s and it is not a Mercedes-Benz: the archive in Stuttgart holds nothing on it, and on that narrow point the company is entirely right. What the car produced instead was a marque. Isdera still exists — an engineering office, these days in Saarbrücken, still fond of gullwing doors.
One man's unbuildable drawing, thirty finished cars, and a badge fitted without asking that nobody ever got round to unscrewing.