The C 111-III was to demonstrate the performance of the turbodiesel engine which Mercedes-Benz was about to launch in the 300 SD. With convincing results: In tests in Nardò, Italy, in 1978, the C 111-III established nine world speed records over different distances and time spans. Over the 500-kilometer (311-mile) distance, the car reached an average speed of 200.1 mph.