In the late 60s, Mercedes had a series of unique drivetrains and other technological advancements it was looking to develop. In 1969, Mercedes developed the C111 as the platform to house and test these innovations. The first version hosted a Mercedes-designed three rotor direct injected Wankel engine. They placed an aerodynamic fiberglass body shell over the platform, with the engine rear-mid mounted. The first cars were painted orange metallic, specifically to attract attention.
The following year in 1970, the second iteration of the C111 appeared, this time equipped with a four-rotor Wankel producing 370 hp. The car was capable of speeds of 185+ mph, and was recorded with a 0 to 60 time of under 4.8 seconds. Seriously quick even by today's standards, let alone for nearly 45 years ago.
The dramatic appearance was not typical for Mercedes in that era. When the car was shown at the 1970 Geneva Motor Show, it was to great acclaim. Many people believed it to be the potential long-time-coming replacement for the legendary 300 SL Gullwing.
Ultimately with increasingly challenging emissions standards and ever-more expensive gasoline, Mercedes decided not to proceed with the Wankel engine. Instead, it turned to diesel engines for the second generation - the C111-II cars. Over time, they continuously refined the aerodynamics, ultimately giving the second generation C111 a very slippery drag coefficient of .183. In that body configuration, equipped with a 230 hp inline five cylinder turbo diesel, the car broke nine diesel and gas speed records. It eventually reached 200 mph in 1978. At one point on the Nardo Test Track, it maintained an average speed of 186 mph for over 12 hours - while averaging just under 18 miles per gallon.
Later in 1979 they added further, more visible aerodynamic refinements, including spoilers, tailfins, and a heavily modified front end. The C111-IV version was equipped with a 500 hp twin turbocharged 4.8 liter V8. With the improved aero, and that drivetrain, the C111 would set yet another record at Nardo - this time with an average lap speed of 251 mph. That's Bugatti Veyron speeds 30 years before the Veyron.
Mercedes introduce a new platform in 1991 at the Frankfurt Motor Show with the C112, but was thinking of it more as a market test of a new car. The new vision utilized a mid mounted 6.0 liter V12 engine. Mercedes even went as far as to accept deposits for the car, but ultimately decided not to proceed with production.
To this day, the Mercedes C111 may be one of the most flexible, utilized, record-breaking concept cars produced.