Although it may sound like an underground rave from the 1990s, the Techno-Classica is an annual get together of some pretty special classic cars in Essen, Germany. This year’s event in April will play host to 1,250 exhibitors - the most exciting of which could be Mercedes.

The Stuttgart carmaker is set to bring each member of its incredible C111 family of development cars together in one place for public viewing. The C111 was initially introduced to the public at the Frankfurt Motor Show in 1969, and Merc engineers then spent the next decade testing a whole host of engines and technological developments on different iterations.

But just what made those C111s so special? Click through to take a look, but be prepared for much 70s wedginess…

Mercedes C111-I

The iconic shape of the original C111 was the result of slippery aerodynamics testing by Merc engineers. However, perhaps the most unusual development was the three-rotor Wankel engine under the bonnet…

Mercedes C111-I

Thanks to its gullwing doors and bright orange paint, the C111 concept made quite a splash when it was revealed. But it was never set for production.

Mercedes C111-II

Instead the car spawned new editions to act as different test beds. The second utilised a four-rotor Wankel engine with 350hp, taking it to a top-speed of 300km/h…

Mercedes C111-II

Rotary engines are notoriously inefficient and unreliable though, so Merc ditched their development plans and, at some point in the decade, fitted the C111-II with the 3.5-litre V8 from its sedan cars. Incredibly it’s fully road-legal and still running, at least it was when we drove it back in 2015…

Mercedes C111- II D

In total there were six examples of the C111-II. The one you see above was given a turbocharged and intercooled version of Merc’s 3.0-litre, five-cylinder diesel, producing 190hp…

Mercedes C111- II D

Merc used it for a record-breaking 64-hour drive at Nardo, where the car managed average speeds in excess of 250km/h.

Mercedes C111-III

The third iteration from 1978 continued with the diesel development - getting more power and an even more slippery body, complete with uber-cool shark fin…

Mercedes C111-III

In April of the same year the C111-III set nine different world speed records in another visit to Nardo.

Mercedes C111-IV

By the time Mercedes got around to building the final C111 in 1979, they were seemingly obsessed with record breaking. The IV had a new (rather large) front splitter and two shark fins at the back to improve aero…

Mercedes C111-IV

It also got the stonking 500hp, 4.8-litre twin-turbo V8 from an S-Class and hit 400+km/h around a banked circuit. A fitting way for the C111 mules to bow out.

STORY Greg Potts