Mystery behind Mercedes-Benz’s C111 that created a sensation in the 70s

The Mercedes Benz C111 is an amazing, wedge-shaped piece of Benz history

The C111-II which followed the original in 1969, was restyled by Mercedes-Benz to incorporate a new bonnet and an extra engine rotor that allowed it to reach speeds of 100kph in 4.8 seconds.

It is difficult to comprehend the sensation Mercedes-Benz caused when it revealed the C111 at the International Motor Show in Frankfurt in 1969. People who were there tell stories of eager potential customers writing blank cheques and handing them to Mercedes-Benz’s staff. It seems no amount of money could buy the exotic, mid-engined, gullwing-doored wedge, as despite being exhibited at subsequent shows, and updated over a period of years, the C111 never reached series production.

If it had the supercar landscape as we know it now, it might have been very different. Mid-engined road cars were rare, the Lotus Europa and Lamborghini Miura among the very first, but the C111’s exotic engine location wasn’t the only revolutionary element of its make-up; the engine itself was very unusual.

Mercedes-Benz fitted the C111 with a Wankel rotary engine, the compact, light powerplant featuring three rotors and turbocharging for a 280hp peak power output. Add Mercedes-Benz’s signature gullwing doors – a nod to the company’s most-famous 300SL coupé – and it’s little wonder the C111 had potential customers so eager to buy one.

That it never reached production is part of its mystique. Unlike so many show cars that grab the headlines one day and are forgotten soon after, the C111 had staying power. Its star shone brightly, thanks in no small part to Mercedes-Benz using it as an experimental vehicle. The C111 can genuinely claim to have impacted on all modern Mercedes-Benz production vehicles since, as it was used to test all manner of innovations, from anti-lock brakes to air-conditioning systems.

The C111 also featured innovative anti-dive suspension technology that found a home in its more sober production relations.

About 14 C111s were built between 1969 and throughout the 1970s. The C111-II followed on from the 1969 car very quickly, being shown at the Geneva International Motor Show in March 1970. Slightly restyled to incorporate a new bonnet with deep venting in its centre, the engine under the flying buttressed rear gained another rotor for a maximum output of 350hp, allowing it to reach 100kph in 4.8 seconds and 300kph. Those numbers were sensational back then; the Lamborghini Miura P400S, which was built between 1968 and 1971, trailed that top speed by 19kph and took 0.7 seconds longer to reach 100.

The decision not to put the C111 into production came down to a number of factors. Mercedes-Benz has always had safety as a core brand value and the C111’s rather extreme nature didn’t really fit into that. Nor did the need for the rotary engine’s meticulous upkeep, and its notoriously poor fuel consumption – the C111 arrived just in time for a looming global fuel crisis. Its destiny might have seen it used as an experimental and developmental vehicle, but the development staff clearly had fun with it.

The Wankel engines were shelved and in their place Mercedes-Benz engineers placed five-cylinder turbo diesels based on the 80hp OM617 unit. Intercooling and some other revisions saw the C111-IID offer 190hp and 373Nm of torque, which, when combined with a lightweight glass fibre body and tubular chassis, allowed it to break nine speed records at Italy’s Nardo test facility. More speed would come too, a 230hp C111-III of 1978 gaining an additional intercooler for that power increase, silver paint and a body designed to scythe through the air as efficiently as possible in a bid to break more speed records. In its fifth and final form, Mercedes-Benz would go all-in on chasing speed, dropping a turbocharged 4.8-litre V8 petrol engine with 500hp in the rear, while adding an even more radical streamliner-style body.

In 1979, Dr Hans Leibold would take that car around the Nardo test facility’s 12.5km ring with an average lap speed of 403.7kph. That’s an incredible number today, let alone 36 years ago. No such high-speed glory for the orange C111 parked outside today. Look closely at the windscreen, if you can take your eyes off the rest of it, and there’s a thin orange line betraying a radio antenna. It’s hooked up to the Becker radio inside, indicating that this C111 was driven around testing how the reception worked with the new integrated aerial. It was also used for testing air conditioning and for ABS brake development, so its engineer back in the 70s would have been comfortably cool, entertained and safe. In the world of automotive testing, being given the keys to a C111 would have been like winning the jackpot.

Today I can appreciate how that feels. The C111-II parked outside Mercedes-Benz World in Surrey, UK, is there for me. I’ve got it for the day: it’s escaping its usual museum display or storage and getting some exercise. It’s off to the Goodwood Festival of Speed at the weekend for a brief static appearance before being taken back to Mercedes-Benz’s classic centre and put away for a while.

Always a car I’ve admired, I’ve only ever seen one under electric light, indoors and on a plinth. Seeing it parked outside, on the road, at the right height and under sunlight, reveals just how pretty it really is. Its wedge-like front, with hidden pop-up headlights, proud Mercedes-Benz star and triple vents on the leading edge droops, much like the nose on that other 70s icon, Concorde. The semi-matte finish paint, which fills the centre of the bonnet where two vents plunge dramatically for additional cooling, featured first on the C111-II. The front is its most dramatic view, but it’s the rear that captivates me. The upright, almost Kamm tail, with its simple round lights and black grille between them, is precise in its simplicity, combining with that rear deck very neatly.

The scalloped rear wing’s intake is discretely integrated fore of the rear wheel, while the flying buttress rear engine cover with its concave matte finish black deck, creates a unique styling signature. The C111 would look entirely different without its contrasting black elements. That it remains a contemporary-looking vehicle today is testament to how radical it must have looked when it was first revealed. Only its tiny 15-inch alloy wheels with their large profile Michelin XWX tyres and the pop-up headlights betray its vintage; such lights consigned to the past, thanks to the onward march of safety legislation.

There’s evidence of its hard life as an experimental vehicle. Look closely at the door shuts and there’s rubbed paint – the body-on-frame’s relative lack of stiffness revealed when opening and closing the doors on any surface that’s not flat, such as the banking at Brooklands, the world’s first purpose-built racetrack. This particular car might not have broken any speed records, but Brooklands’ steep banking, so evocative of a time where the quest for speed was a brave endeavour rather than a frivolous pastime or sport, feels right. The C111-II looks at home here, the occasional school party visiting the banking getting a rare treat and seeing a priceless rarity driving on the classic track. The C111-II’s custodian, Matthias Chwal, from Mercedes-Benz’s Classic Centre, looks on nervously. Little surprise given the car is insured for around $6 million (Dh22.04m), but it’s only running gently for the cameras here.

Getting in over the wide sill isn’t too tricky, thanks to the space above from the gullwing doors. Once inside, the dashboard is simple, though the rev-counter’s 10,000rpm maximum isn’t correct, as there is some red paint applied at 6,000rpm. Chwal says the Wankel engine that once powered it resides in storage, as the parts supply is gone and it is too precious to use. In the back sits the period-correct M116 V8, which was used in the R107 Mercedes 350 SL, as well as being dropped into the C111-II back in the 70s. The 3.5L V8 produces a respectable, if not prodigious 200hp, so it’s quick rather than genuinely fast. Chwal has asked respectfully that it’s not driven over 130kph and that there’s “no drifting”. Neither crosses my mind, even if the opportunity to lap the C111 fast on Mercedes-Benz World’s test track allows it to be driven harder than might be sensible on the road.

The steering is beautifully weighted and rich in information, its pleated leather rim an absolute delight. The ride is exceptional; nothing today with any pretensions to the C111-II’s performance can deliver anything like the comfort it offers. There’s plenty of lean in the corners as a result, but that anti-dive suspension technology keeps it flat even under heavy braking. Grip levels are high, the steering precise, the brakes strong and the V8 engine sounds fantastic through the thin glass fibre firewall.

The dog-legged five-speed manual transmission needs a button pressing on top of the lever to select first; it’s long across its gate and needs practice to slot in to the next ratio. You get more from it the more effort you put into it, the C111-II demonstrative of a time when you had to really drive cars – even the most cutting edge ones.

In the 70s, with the Wankel engine, or one of those torque-rich diesels in it, the C111 must have felt other-worldly quick; indeed, I’m pretty happy that it’s not in the back today. It’s incredible to think that a development of this car averaged over 400kph around Nardo in its final 500hp, V8 turbo specification. Dr Hans Leibold, you are a better man than I am. What’s fascinating is what could have been; the C111 is an icon perhaps because of its non-production status, a beguiling evolutionary step in the supercar that had everything and more to shake up the Italian hierarchy. There is no doubting the fact that there would have been a good few relieved people at Ferrari, Lamborghini and Maserati back in the 70s when Mercedes-Benz decided not to cash in those cheques.

The C111-II was photographed on the banking of the famous Brooklands Track at the Brooklands Museum, the birthplace of British motorsport (www.brooklandsmuseum.com).