The Mercedes-Benz 300 SD became the first passenger-production automobile with a turbocharged diesel engine when it launched in 1978.
The 300 SD was a diesel version of the W116 S-Class and was initially developed for the North American market. Its turbocharged five-cylinder diesel engine improved performance over naturally aspirated diesel cars while retaining the fuel economy and durability associated with diesel power.
Mercedes-Benz had already offered diesel passenger cars, including the 240 D and 300 D. The 300 SD's distinction was adding a turbocharger to a diesel engine in a series-production passenger automobile. Turbocharging forced more air into the engine, allowing greater power from a relatively small displacement.
The model arrived during a period of fuel-price concern and helped establish Mercedes-Benz as a major pioneer of diesel passenger-car technology. It should not be confused with later diesel performance models from Volkswagen, BMW, or Peugeot.