1976 Mercedes-Benz C111-IID

Now isn't a good time to have a crisis of confidence.

Once we flail into the driver seat of the Mercedes-Benz C111 record car, a Mercedes technician gently lowers the gullwing door into place while we scan the 20-plus gauges on the instrument panel.

We're told categorically that the most important thing is not to get in anybody's way. In a car that sits just 44 inches off the deck and with only one mirror, this will be no mean task, especially as we'll be tilted on our axis as camouflaged Mercedes-Benz prototypes hurtle past at obscene speeds. Here in northern Germany, the ATP Papenburg test track has epic straights in its 7.6 miles, but it's the four lanes of banking that matter.

And we're in a genuine record-setter, the Mercedes-Benz C111-IID, a futuristic sports car that set a record for diesel-powered cars in 1976 by averaging 160 mph for 10,000 miles.

The C111 is the midengine sports car that Mercedes-Benz never built, though it came oh so close.

Speed Comes With a Clatter
With fuel pump primed and ignition on, this most rarefied of exotica sounds anything but. There's a hollow clatter, a detonation of sound on start-up before the engine idles at a registered 1,000 rpm. Which is actually 966 rpm — it says so on a bit of tape next to the rev counter. With a tall 1st gear on the five-speed manual gearbox and a clutch that is either in or out, we fully expect to stall the inline-5 diesel engine. Luckily we're able to lurch forward in a series of surges like a kangaroo as the revs reluctantly rise before shifting into 2nd and accelerating rapidly without exceeding the mandated maximum of 5,100 rpm.

Without a filter between brain and mouth, our first run through the Papenburg banking brings with it obscenity-laden elation and a slight case of the heebie-jeebies. The C111 is effortless to drive, requiring only a slight counterintuitive correction as you drive into the banking before letting it settle on its given course. Just don't try and change lanes. By about the 11th lap the thrill of speed has slackened a little, but then two Maybach test hacks blast past us with just inches to spare. We're travelling pretty damn quickly, especially in a car that's 40 years old; just not quickly enough.

It's at times such as these that you fully appreciate just how good the good guys really are. Not least Dr. Hans Liebold, Joachim Kaaden, Guido Moch and the legendary Erich Waxenberger. On June 12, 1976, these Mercedes test jockeys braved the banking at Italy's Nardò test facility in this very car. After 64 hours of near constant driving, with a driver change every two and a half hours, they had beaten or established eight new speed records and travelled more than 10,000 miles. And averaged close to 160 mph. Not bad for a diesel.

Midengine Is the Future
Backtrack to 1965. Mercedes-Benz had been absent from top-flight motorsport for a decade following the factory team's withdrawal after the 1955 disaster at the 24 Hours of Le Mans and former competition chief Rudolf Uhlenhaut was now head of passenger car development. He craved something to get his teeth into and finally persuaded the company to step into the future.

A new, more youthful engineering generation would assume control at the development branch in Unterturkheim. Uhlenhaut was particularly keen to explore the potential of a midengine layout, the configuration that every car company in the world had embraced in the wake of the midengine revolution in motorsport. A design study had first been mooted in 1964 but it wasn't until 1968 that the proposal, initially code-named C101, really gained traction.

Had Mercedes put the C111-II into production, it would have come along well before the BMW M1.

This new breed of Merc would be powered by a Wankel rotary engine, Daimler-Benz being one of many companies to have acquired a patent license for the design back in 1961. The car would also act as a test bed for such things as composite construction, ABS braking and suspension configurations. Full-scale production wasn't on the agenda, yet this engineering hack was intended to be a show-stopper nevertheless.

Midengine road cars were still considered daring in the 1960s. Uhlenhaut's team had evaluated established marques, acquiring a Lotus 47 among others, but typically went its own way with a semi-space frame chassis that had deep sills to provide adequate structural rigidity. Suspension was via unequal-length wishbones and an antiroll bar up front, with unequal-length transverse links, upper and lower trailing arms and an antiroll bar out back. Coil springs were used at every corner. Wankel power came from an extremely compact, 280-horsepower three-chamber rotary engine, which displaced 600cc per chamber (the equivalent of a 3.6-liter piston engine).

The Shape of the Future
With the grubby bits sorted, the C111 was starting to take shape, even if that shape was best viewed at night. The original test mule — dubbed the "Tin Box" — wasn't a looker, as the angular aluminum bodywork was essentially in place only to keep the rain out. The prototype took to the road on April 16, 1969, and future record-breaker Liebold flogged it around the Nürburgring and Hockenheim circuits barely a month later. Meanwhile, the body engineering department under Werner Breitschwedt and Karl Wilfert set about transforming Bruno Sacco's design rendering into three-dimensional reality.

In July 1969 the first definitive fiberglass body shell was glued, riveted and screwed into place and then tested in a wind tunnel, where it recorded a drag coefficient of 0.335. Such was the enthusiastic reception within the company that the car was prepared for demonstrations to the press at the Frankfurt auto show in September.

Predictably, reaction was one of jaw-slackened disbelief. To most onlookers, this gullwing flight of fantasy was a dream car in every sense, even if Merc insiders remained mum over whether it would ever reach volume manufacture. In 1970, a restyled variant with a 350-hp four-rotor Wankel — the CIII-II — broke cover at the Geneva auto show, and it seemed ever more likely that the car would be offered for public consumption.

The big draw for the management was making use of the Wankel engine to which the firm had devoted vast resources. The C111 was the ideal platform with which to usher in this brave new world before it found a home in a range of more conformist products. Chevrolet undertook the same adventure in 1971, which led to two midengine, rotary-powered Corvette showcars.

The Future Changes Shape
Unfortunately, there remained serious doubts that the rotary engine could ever provide the sort of reliability and longevity expected of a Mercedes-Benz. Its hellacious thirst for fuel also counted against it, as did proposed U.S. air emissions regulations. The other alternative was a regular piston engine, and one of the original prototypes was fitted with a 4.5-liter V8.

Sadly, though, the board vetoed each scheme. Taking a risk on a car so alien to everything else in the model range was, well, too risky. Instead, it allowed a second batch of cars to be built, but only for research purposes. Since the 1973 fuel crisis nearly extinguished the market for supercars entirely, you can understand management's decision.

Of the first two series of C111s, seven were of the C111-II configuration. Just to confuse matters, this is the one and only C111-IID. The car we're driving today was the first example of the second batch of prototypes and was relegated to a life of dusty stasis in the experimental department's backroom. Then it was resurrected in 1976 to become the centerpiece of Daimler-Benz's campaign to modernize the image of its diesel engines. What better way to publicize the potential of its innovative inline-5 diesel than with a few speed and endurance records?

So out came the rotary and in went a humble diesel unit taken from the 240D sedan. With the addition of a turbocharger from Garrett AiResearch, a slightly more slippery body and experimental Michelin tires, the C111-IID collected all international records in the 3.0-liter diesel class. Averaging 157.161 mph on the 7.8-mile Nardò circuit during the round-the-clock record run, the 2,912-pound C111-IID had more than proven its worth. Even more so when you consider it also averaged 11.9 mpg.

The Sports Car of Today
It's not exactly hot outside as we're driving, but this fabulous machine may as well be hermetically sealed. It gets very toasty, very quickly. But it's such a fabulous device, you can forgive it anything.

Back then, the arrival of any supercar was an event, but all too often what looked avant-garde when new appeared preposterous just a few years down the line. Just look at the Lamborghini Countach. The C111 in any of its guises didn't require add-ons or other stylistic pestilence, and that fetching shade of "Weissherbst" (a reference to a German rosé wine with an orange color) expresses the hedonistic glamour of the 1970s.

Sure, this particular car is a little gawkier than its siblings, thanks in part to the cut 'n shut nature of the rehashing for record-setting, with exposed headlights and skinny tires. Yet even without its make-up done, the C111 still leaves you weak at the knees.

The C111-III came together as a dedicated record-breaking version of the car in 1977, still with diesel power, and it set further records thanks to a top speed of 203 mph. Finally the C111-IV appeared. Powered by a twin-turbocharged 4.5-liter V8, this variation on the theme was driven to 250.918 mph at Nardò on May 5, 1979, to set the world closed-course speed record.

Had Mercedes taken the leap and put the C111-II into production, it would have beaten BMW to the supercar firmament long before the BMW M1 ever broke cover in 1978. But when the Bavarian marque lost a fortune on its entirely conventional supercar, the future for midengine cars didn't seem so bright. The Mercedes-Benz C111 might have been more like a dead end than a pinnacle of engineering achievement, but this beguiling oddity was creatively triumphant even as it became commercially marginal. And that still counts as a victory.

Portions of this content have appeared in foreign print media and are reproduced with permission.