Back in the 1950s, it seemed like Mercedes would rule the flagship sports car roost forever. Its 300 SLR race cars were virtually unbeatable and its 300 SL road cars garnered appreciation from fans and celebrities alike. Sadly, in the midst of all this success, disaster happened: A crash at the 1955 24 Hours of LeMans involving a 300 SLR killed 84 people, and Mercedes withdrew from motorsport following the season. Although 300SL production continued through 1963, the brand didn’t make another flagship sports car customers could buy until the CLK GTR Straßenversion. However, a fire burned deep inside Mercedes-Benz for something above the SL in performance, but it just never got big enough for a true production car. These are the largely forgotten Mercedes-Benz gullwing successors of the 20th century.
1965 – Mercedes-Benz SLX
Just seven years after that fateful day at LeMans, Mercedes-Benz decided to take another crack at a high-performance coupe. Like the 300SL, it had funny doors, incredibly tall sills, and slippery compound curves. Unlike the 300SL, it had its engine behind the driver. The SLX wasn’t poised to take the “first supercar” title from the Lamborghini Miura, but it certainly wasn’t like anything the three-pointed star had made before.
Styled by Paul Bracq and Giorgio Battistella, the SLX was meant to take the fight to the Porsche 904. Porsche’s first ground-up mid-engined car is a lightweight, underappreciated masterpiece, and the SLX could’ve been every bit as good. Sadly, after a wooden model was built in 1965, the entire project was shelved. A changing of the guard in the R&D department put all existing projects on hold, and the SLX just wasn’t right enough to survive the direction change. However, it became the genesis for an iconic series of protoypes that saw everything from Wankel to diesel power – the C111.
1978 – Mercedes-Benz C111-III
Knock-knock, it’s the 1970s, and new legislation was about to reshape the automotive industry. From emissions restrictions to basic safety requirements, the car as we know it was about to change. Mercedes, in its wisdom, decided to get ahead of the problem by building a series of development cars called C111. The first of these mid-engined testbeds was powered by a Wankel rotary engine as everyone from GM to Citroen thought this high-revving engine would be the future of internal combustion. Obviously it wasn’t, or we’d all know about eccentric shaft throw, but it was the style of the time.
The first C111 came on the scene with a three-rotor engine and the second C111 got a four-rotor unit, but the madness had only begun. Yes, these were bright orange Wankel-powered mid-engined performance cars with gullwing doors, but they seemed positively tame compared to what was next. While the later C111 versions are less remembered than their earlier brethren, they’re even more astounding.
If the C111 II looked like a concept car, the C111 III looked like nothing you’d ever see on the road. While it ditched the Garfield colorway for stealthy silver, it grew preposterously extroverted streamliner bodywork reminiscent of the Jet Age concepts of Motorama. With faired-in arches, a giant rear fin, and a black band around its belly, this C111 looked like a shark for the road. Instead of a Wankel engine, this prototype got a tuned-up diesel more in tune with the consumption-conscious vibe of the 1970s. Mercedes let it off the leash at Nardo in 1978 and came back with an average speed of 321.86 km/h over the span of 500 kilometers. That’s 199.995 mph in Imperial units. Pretty good, but Mercedes knew it could do better.
For the C111 IV, Mercedes went even crazier with a second fin and even longer bodywork. What’s more, it took the 4.5-liter V8 from the S-Class, punched it out to 4.8 liters, bolted on two turbochargers, and headed back to Nardo in search of glory. Once the dust settled, the C111 IV had achieved a top speed of 403.978 km/h or 251 mph – Bugatti Veyron figures in the 1970s with just 500 horsepower on tap. That’s an extremely scary speed at Nardo considering neutral steering in the highest lane on the banking is achieved at 124 mph, so hats off to the test driver for having the nerve to stay in it.
1978 – The CW311
When is a Mercedes-Benz not a Mercedes-Benz? When it’s designed by a man from Porsche. Welcome to the CW311, a fan-built project gone berserk. In 1972, engineer Eberhardt Schulz decided to work on his own gullwing successor, possibly one with blackjack and hookers. Sketched out by Porsche Design employee Schulz and built by BB Auto Exclusiv Service, the CW311 made its debut at Frankfurt in 1978, and Mercedes wasn’t biting.
It’s a shame that Mercedes didn’t take Schulz up on his mid-engined supercar, because it had all the goods of the era. The engine was the formidable 6.9-liter V8 from the 450 SEL 6.9 fettled by AMG to the tune of 370 horsepower. An earth-shattering number for the 1970s. It came mated to a five-speed ZF transaxle, and the whole powertrain assembly was bolted to a tubular space frame with independent suspension at all four corners. The result was a monster capable of zero-to-60 in under five seconds and a top speed of 198 mph. It could’ve very well been the fastest car on the road.
However, the story doesn’t end there. Several years later, Schulz stretched the wheelbase out, slapped his own badges on the car, and called it the Isdera Imperator 108i. It used a series of smaller V8s rather than the monstrous 6.9-liter unit, but it could still haul the mail with up to 390 horsepower on tap. A mere 30 were built over a nine-year production run, but each one was something special.
1991 – Mercedes-Benz C112
By the early 1990s, the supercar revolution was really kicking into high gear. From the Lamborghini Diablo to the Jaguar XJ220, everyone was getting in on this ultra-expensive club of speed. Naturally, Mercedes-Benz wanted a crack at it, so it built the C112 – a V12-powered monster with more luxury than any supercar before. Admittedly, it wasn’t particularly exciting to look at, but it was designed by Bruno Sacco and the team at Mercedes’ skunkworks DAS division to be road-legal everywhere and offer truly massive performance.
Featuring the 402-horsepower M120 V12 from the 600SL mated to a six-speed manual transaxle driving the rear wheels, this thing had the goods to be ‘90s supercar royalty even before getting into all the onboard tech. We’re talking about an air brake, four-wheel-steering, active hydraulic suspension, and a bonded aluminum chassis. Heady stuff for 1991. Zero-to-62 mph happened in a claimed 4.9 seconds and top speed was 192 mph, good enough to almost be on level footing with a Ferrari 512 TR.
What’s more, it’s said to have passed California’s emissions standards, came with GPS and tire pressure monitoring and all the computerized gizmos you could want, and of course had gullwing doors. It seemed like it could’ve been the ultimate Munich to Monaco mile-muncher, if it weren’t for one detail – amidst the complication of integrating all the electronics, Mercedes didn’t spend any time on luggage space.
Unlike the SLX and C111, Mercedes actually took orders for the C112, and 700 are claimed to have poured in. However, that wasn’t enough to convince Mercedes to actually build the damn thing, and plans for production were shelved. What a shame.
While the CLK GTR Straßenversion of 1998 was an astounding homologation special that opened doors for later Mercedes supercars, I can’t help but wonder what could’ve been if Mercedes put any of its 20th-century flagship performance prototypes into production. Perhaps kids would’ve had posters of the C112 on their walls rather than 993 Turbos and XJ220s. Still, all these cars that never were serve up an important lesson: You never quite know what’s going on behind a car company’s doors until it happens. However, to forget these amazing cars feels like a shame. From the SLX to the C112, they all paved the way for some truly amazing production cars.
(Photo credits: Mercedes-Benz, BB Auto Exclusiv Service)
Support our mission of championing car culture by becoming an Official Autopian Member.
Watch The Mercedes-AMG One Smash The Nürburgring Lap Record Under Apparently Seriously Sub-Optimal Conditions
Someone Snuck A Canadian Mercedes-AMG A35 Hatchback Across The Border And It’s Now For Sale In America
Mercedes-AMG Goes Absolutely Insane With The Jacked-Up, Portal Axle-Equipped G63 4×4 Squared
The Mercedes-AMG S63 E Performance With 1,055 Lb.-Ft. Of Torque Is A High-Tech Dinosaur In All The Best Ways
The 671-Horsepower Mercedes-AMG C63 S E Performance Is Powerful But So Heavy
Got a hot tip? Send it to us here. Or check out the stories on our homepage.
We’re not even going to mention the CW311’s periscope rear view mirror? (A feature that carried over to the Isdera Imperator.)
The CW311 was the car in the artwork for the original SpyHunter arcade game.
Interesting article, for years all I knew of these vehicles was their numbers from a set of Top Trump cards I had as kid.
The C112 looks like a predecessor to the AMG 1 (? Can’t remember it’s name, the f1 engined hypercar)
Obviously, the Autopian needs to hire the proofreaders.
“Just seven years after that fateful day at LeMans…”
That would be 1955, not 1958, so it should be ten, not seven, years.
“…the CW311 made its debut at Frankfurt in 1978,…”
No, IAA Frankfurt was held during the odd-numbered years (from 1992 onward, the IAA for commercial vehicles was held on even-numbered years in Hannover).
The CW311 B+B was publicly introduced in 1978. When Mercedes-Benz threatened the legal sanctions against B+B, the three-point star ornaments and Mercedes-Benz nameplates were removed when the CW311 made its appearance at IAA Frankfurt in 1979.
“The engine was the formidable 6.9-liter V8 from the 450 SEL 6.9 fettled by AMG to the tune of 370 horsepower.”
No, it was 6.3-litre M100 V8 fitted to the 600 (Großer Mercedes) and 300 SEL 6.3, not the 6.8-litre V8 engine from 450 SEL 6.9. Despite the “6.9” nomenclature, the engine is actually 6.8 litres (6,834 cc).
You might very well be right with the details, but no need to be aggressively superior in tone.
Perhaps you should offer your services as a proofreader/expert.
What a great article, and thank you for telling me more about these cool old concepts. This is the kind of thing I come to the Autopian for, and it perfectly fits the idea of a website built for enthusiasts.
I’ll take this over camper articles and Kia reviews any day.
I have always known the car you have labeled as the 1965 SLX as the 1969 C111 Designstudie “Design Prototype” by Bruno Sacco. I saw it in the museum labeled as that.
The C111-III had a drag coefficient of 0.19.
A production version of this could have been done using the 5-cylinder engine from the 300SD, could have been tuned for 300 horsepower, and very likely would have gotten close to 60 mpg on the highway. This would have been a perfect halo car for the 1970s fuel crisis. Astounding fuel economy to go with a 200 mph top speed.
Hell, a cheaper version using the 71 horsepower 4-cylinder from the 240D probably would have seen 130 mph in stock tune, and gotten similar economy to what was hypothesized above. Which would have been more than acceptable for the time period, regardless of how long it took to get there. It would have been suited for the Autobahn just fine with such low horsepower.
What could have been…