Back to the Future
Driving the Mercedes-Benz Museum’s priceless C111-II on the Colorado Grand
Article Gary Anderson
Images Royce Rumsey and Gary Anderson
Automobiles are designed to be driven. If your classic-car collection includes a 1970 C111-II, a rare experimental prototype built 45 years ago, you’ll want to rethink that stratagem. You might take it out – if at all – for photo shoots, operating it very carefully for short distances.
But if you’re Michael Bock, director of Mercedes-Benz Classic Center, you would have it mechanically refreshed and then shipped to the United States to drive in the Colorado Grand, an annual rally event that covers more than 1,100 miles in traffic on open roads through the American West. That’s what Bock did last September. I was honored to be his co-driver.
Backing up a bit, what was the genesis of this sleek and eye-catching sports car? What is it like to drive? And why didn’t Mercedes-Benz manufacture the car when people wanted to buy it – cost no object – in 1970?
Exploring alternatives
During the late 1960s, Mercedes-Benz built a broad range of high-quality and reliable sedans. For Rudolph Uhlenhaut, director of production car development (he was the one who drove a sporty one-off 300SLR everyday), it can’t have been a very exciting time. Perhaps that’s why, sometime in 1967 or 1968, he obtained board approval for an experimental prototype to explore new concepts of automotive development.
At the core of the prototype would be a 3-rotor Wankel engine, for which Daimler obtained a development license. Many people in the industry believed this compact, lightweight and simple engine could be the automotive propulsion unit of the future. The engine would be mounted ahead of the rear axle in a mid-engine configuration that was known for its handling advantages; it had never been used by Mercedes-Benz.
The car would be built on a standard steel frame – though Mercedes was by then committed to unibody chassis structures – with body panels made of fiberglass, a material developed to production levels by General Motors for its Corvette sports car.
The car would also break away from the stolid styling cues used in all the company’s sedans. Instead, Mercedes-Benz embraced the fringe, adapting the aerodynamic wedge shape used by several Italian design houses and rumored to be under development at the same time in BMW’s design studio. The perspective would include protective roll hoops above the windshield and behind the passenger seats, anchoring gullwing doors like those on the original 300SLs.
Underneath, engineers experimented with new independent front and rear suspensions, 4-wheel disc brakes and an anti-lock braking system. The transmission would be the standard ZF 5-speed manual transmission used in the 280SL, mounted backward behind the rear axle with extended linkage to the console-mounted gearshift.
Clearly, Mercedes-Benz engineers and designers would be getting their money’s worth in this on-the-road test bed, even if the prototype was never produced. The project was approved even in the face of international economic turmoil. In early 1969, a crude mule to test the suspension and motor mountings was assembled out of steel as lead Mercedes designer Bruno Sacco put the final touches on a fiberglass body.
In September 1969, the C111 was unveiled at the International Automobile Assembly (IAA) in Frankfurt and caught the attention of the global press. With the striking copper-gold color that the stylists called “rosé wine,” its sleek nose and gullwing doors, the car was the headliner of the show. Even though the real news was the Wankel engine, reputed to be capable of more than 300 horsepower and a top speed in excess of 160 mph, the press focused on the car’s limited visibility, unfinished interior and the fact that the small luggage compartment was not insulated from the engine’s heat: As one journalist noted, the car couldn’t carry a pound of butter home from the store without melting.
But Mercedes-Benz designers and experimental engineers were far from finished with the car’s development. The following spring, the C111-II was unveiled at the Geneva Motor Show to more positive reviews.
The Wankel engine had been upgraded to a 2,400cc 4-rotor version, capable of 400 horsepower and 330 pound-feet of torque. The zero-to-60 mph time was reported to be 4.7 seconds, with a top speed of 186 mph at 7,000 rpm, astonishing specifications for the time, especially in a car that looked production ready.
Given that the new 3.5-liter M116 engine was also introduced in the 280SE 3.5 at that same Frankfurt show in 1969, it was clear that the fuel-injected V-8 was installed in one or more of these C111s to produce baseline results for comparison with the Wankel engines.
Sacco made changes to the body style and interior to drive home the point that this car could be produced and sold. The buttresses sweeping back from the reinforced roof and gullwing doors were opened for visibility. The interior was completely finished in a fashionable houndstooth check, and included a Becker radio and air conditioning.
An initial 50-unit production run was hinted to the press: The possibility that this car, though called an experimental test-bed prototype, might go into production seemed very real. It was even reported that during the show, a number of Mercedes owners signed blank checks to reserve a car should the company decide to build it.
Experimental development
Production was not the primary goal, however. After the Geneva show, the cars – with more than a dozen built – were used as platforms for development of the Wankel engine. But by 1973, engineers’ inability to overcome the inherent thermal inefficiency of the engine – translated: It was a gasoline hog – encountered the first oil embargo and a dramatic increase in fuel prices. Wankel engine development was terminated and further use of the experimental vehicle was suspended.
The best possibility for new-engine development at that time seemed to be a passenger-car version of the diesel, so the C111-II was called back to duty as a test platform and publicity generator for diesel power in 1976. With turbocharging and intercooling, the C111-II with the new OM167 diesel engine was able to set 16 world records on the high-speed Nardò Ring test track in Italy, including an average speed of nearly 160 mph over 60 hours.
The basic chassis of the C111-II was adapted to a new highly streamlined body in the C111-III for diesel testing at Nardò in 1978. In 1979, an even more aerodynamic body was developed for the C111-IV, which hit more than 251 mph at Nardò.
Each of the C111’s four versions can be seen today in the experimental car gallery at the Mercedes-Benz Museum in Stuttgart. Nine additional examples of the test car that feature all versions are in the museum’s storage areas.
Resurrecting the C111-II
With Mercedes-Benz planning to introduce the Intelligent Aerodynamic Automobile concept at Frankfurt in 2015, Bock, then head of Mercedes-Benz Classic, proposed that one of the C111-IIs in storage be rebuilt for exhibition in 2015 because of its role in aerodynamic development 55 years earlier. Bock’s idea was to use the car not only for static displays, but also to participate in driving tours.
For this to work, several tasks had to be accomplished. First, the irreplaceable Wankel engine would need to be exchanged for something more reliable. Staying within the Classic Center’s principle of restoring cars to their original condition at a given point in time, the M116 3.5-liter V-8 was selected as a power unit. It could be installed with very minor modifications to engine mounts and in appearance.
All the car’s mechanical aspects were refreshed or replaced as necessary, with particular emphasis on steering, brakes, springs and shock absorbers. Beyond that, new six-point seat belts were installed to match the period racing seats in the C111-II, as well as a fire-control system with internal and external cut-off switches – essentially meeting vintage-car racing safety regulations.
Overall, the C111-II with the 3.5-liter engine is faithful to the appearance and originality of the car as it was unveiled at Geneva in 1970 – and outwardly identical to the unit on display at the Mercedes-Benz Museum in Stuttgart.
Designed for production
What is the car like to drive? Would it have been competitive with other wedge supercars such as the De Tomaso Mangusta that preceded it in 1967 or the Lamborghini Countach that followed in 1974? Would it be a reach to compare it with sports cars of today? Our short answer to both questions is an unequivocal yes.
There’s no doubt that the car is gorgeous, with that sleek nose and short rear deck flanked by flying buttresses evoking speed even when the C111 is standing still. The huge windshield is striking. Compared with today’s supercars – with vents, ducts, wings and splitters on every surface – the overall impression is neat and minimal – almost delicate.
Even the blacked-out areas and uncluttered rear-panel treatment with a blacked-out grille bookended by simple round red taillights invoke understatement and elegance. Not to mention that the eye-catching semi-matte orange-gold finish is stunning.
The large gullwing doors rise smoothly on their hinges, making entrance and exit easier than that in either an original 300SL or the recent SLS Gullwing. There is even a loop handle to pull the door down from inside. The period aftermarket racing seats are lightly upholstered shells with raised bolsters and are very supportive.
The interior trim has excellent fit and finish, even by today’s standards. Though period in appearance – similar upholstery was used in the first Cosworth-tuned 190Es – the houndstooth cloth on the seats and door cards is attractive. Interior space is surprisingly spacious. Shoulder room was more than adequate for two fairly broad occupants. The car’s dashboard looked as well finished as any production car of the era, in part because Mercedes-Benz had used the steering wheel and switchgear from its 1971 production cars for controls. Astonishing for either a museum car or an original experimental prototype, our C111 had complete – and fully operational – accessories, including air conditioning, a complete set of gauges and a period Becker radio, installed vertically rather than horizontally.
The passenger space was comfortable, with enough extra room in the foot well to accommodate a camera bag. That’s fortunate, because in order to ease engine access, the luggage tray in the engine compartment had not been replaced during the car’s refurbishment.
The only issue was a slight lack of headroom mitigated by a raised section in the overhead portions of the doors. Bock had to slide his seat forward as far as possible then tilt the seatback all the way to the bulkhead for headroom. Clearly the interior was designed around a driver and passenger under six feet tall.
Engineered to be driven
On the first day from Vail to Steamboat Springs, I rode as co-driver, reading the maps and route book while taking pictures of other cars and scenery. The early part of the day was spent peering out into the rain swept aside by the elongated single windshield wiper; by afternoon the weather had cleared. The car was very comfortable: I was sorry when we arrived at our destination.
On the second day, Bock asked if I would like to drive the morning stint, heading south into the mountains from Steamboat Springs. Would I! After I got the seat and mirrors adjusted, Bock pointed out the idiosyncrasies of the 5-speed manual transmission. The transmission was behind the rear axle, requiring a linkage with a long front-to-rear bar from the bottom of the gearshift to the transmission, with two right-angle linkages to the gear selector. Reverse and first were in their own left-hand channel, accessible with the switch pushed in the center of the gearshift knob to activate a lockout solenoid. From there, second through fifth gears gripped in a standard H-pattern.
This was awkward at first; the low-torque engine really needed first gear to get moving. Out of downtown traffic and on the highway, I found the car shifted like classic English cars, needing two separate movements from second gear down to third, and then a hesitation as I moved the gear shift across the center of the H, waiting for the back linkage to catch up from third to fourth.
As soon as I focused on driving and stopped thinking about the priceless car I was piloting, I relaxed and began to enjoy this once-in-a-lifetime experience. Acceleration and braking were comparable to any sports car of the period. I definitely had to downshift to maximize torque before attempting a pass or powering out of a corner.
On the other hand, the car was light on its feet and quick to respond to inputs. The mid-engine weight distribution made the car very easy to turn, much more like a modern Porsche Cayman than a 280SL of the C111’s period.
The first question many people asked was, “How fast will it go?” Over the course of four days of driving, Bock became more comfortable with the car and confident of its mechanical reliability: He began to drive it more and more like a true vintage racecar. There was no question that the performance claimed for the C111-II and the M116 V-8 engine by Mercedes-Benz in the initial reports would have been easily achievable.
One characteristic that we both noted was the car’s stability at high speed, unlike many other sports cars of the period. Overall, the C111 was a joy to drive, small and lithe, with lots of feedback through steering wheel and backside. The car was smooth on straight stretches and well planted on curves, with just enough lean to help the driver balance the steering and throttle through a corner.
Why wasn’t it built?
By the last day of the tour with more than 1,100 miles under the wheels – and the opportunity to drive both the 1957 300SL Roadster and 2016 GT S AMG for comparison – Bock and I came to the same conclusion: Mercedes-Benz could have produced the car in 1970 for a price that would have been attractive and, if it had done so, the car would have been a runaway competitive success.
So why wasn’t the C111-II put into production? That’s a mystery; there apparently aren’t any specific memos to indicate why the decision was made to shelve any plans for production. The most obvious problem was that engineers were never able to address the twin issues of Wankel engines: they leaked oil and weren’t fuel-efficient. The first oil embargo arrived in 1973, laying to rest the Wankel program and passenger-car diesel technology, which wasn’t far enough along to be a sensible alternative in a supercar.
Even if the car had been built with the more powerful 4.5-liter V-8 introduced in 1973, the C111 had several other traits that would have doomed its approval by the main board. The primary issue was that it was built of fiberglass without the crumple-zone technology of steel bodies. There would have been no way to guarantee passenger safety for which Mercedes-Benz had established an enviable reputation with its new unibody chassis. To redesign the C111 in steel would have made it too costly and heavy.
Beyond that, Mercedes-Benz had dedicated the two previous decades to carefully building a reputation for reliable, comfortable and practical cars. To offer a European supercar amidst the economic uncertainty of the 1970s was simply too far outside the image of Mercedes-Benz for the board to be comfortable. So the C111-II became a rolling testbed for new diesel and aerodynamic technologies.
But judging from the enthusiastic reception we received from spectators at every stop along the Colorado Grand, the sleek, almost mythical appearance of this unique car has not been forgotten. Now I have my own model of the C111 on my desk at home to remind me that I once had the opportunity to drive this rare supercar as it was originally designed to be to be driven.
Specifications
1970 Mercedes-Benz C111-II
TYPE: Experimental mid-engined rear-drive two-seat gullwing-door coupe
BODY: Fiberglass panels over steel frame
ENGINE: M116 3.5-liter V-8 from 280SE 3.5
TRANSMISSION: ZF 5DS-25/1 5-speed transaxle with limited slip differential
HORSEPOWER: 230 @ 6,050 rpm TORQUE: 231.5 lb-ft @ 4,200 rpm
LENGTH: 174.8 in CURB WEIGHT: 2,735 lb (with Wankel engine)
Images:
The rustic town of Kremmling, Colorado, on the first day of our journey, was the introduction to the many little towns through which the Colorado Grand would pass during our four days on the road in the C111-II.
Of 1,100 miles that we drove, nearly all were on curving two-lane back roads, ample opportunity to enjoy the great handling of the C111-II. Folding dual headlights were typical of the period. Mike Kunz of the Classic Center in California confers with Michael Bock and Gary Anderson at one of the stops.
Route mates included a 1924 Bugatti T35 and 1957 Ferrari 250GT LWB Berlinetta.
Taking a break with the 1962 300SL Roadster from the Classic Center at one of the highest points on the tour.
We’re passed by a 1957 300SL Roadster at Dexter Meadows at C Lazy U Ranch.
The current German license plate is a near match to the original plate number (with the 1955 Hans Hermann Mille Miglia car next to us).
Nate Lander of the Classic Center worms into the car’s engine compartment to add a quart of oil.
The interior of the C111-II was fully finished and comfortable.
The secret to confident touring is a careful check of the car every morning before setting off on the drive.
The Colorado Grand ended where it had started four days earlier, at Lionshead Village in Vail, Colorado. Saturday morning the cars were all on display – our C111 next to the Classic Center’s 300SL Roadster – in the village in the “Concours de Non-Elegance,” proudly displaying the grime of 1,100 miles of travel.