After serial production of the C 111, which had been requested by the public again and again, was finally shelved for a variety of reasons, the second life of this spectacular sports car began. From 1975, the Mercedes-Benz C 111 was to demonstrate the capabilities of diesel engines. To this end, a 3-litre OM 617 turbo-diesel, which was being prepared for series production and was to be used in the US models of the 116 and 123 series from 1977 onwards, was installed as a mid-engine. Whilst the production version had a naturally aspirated engine with an output of 59 kW/80 PS, the turbocharged engine in the C 111 developed 140 kW/190 PS and 363 Nm maximum torque, thanks to a Garrett exhaust turbocharger and charge-air cooler.
On the high-speed Nardò circuit, the C 111, almost unchanged in its outward appearance, broke almost all the records for diesel engines valid at that time in June 1976. Over a distance of 16,000 kilometres, the orange-coloured wedge drove at an average speed of 252 km/h in a 64-hour record drive with four alternating pilots.