The 300SD was a diesel-engined variant of the W126 Mercedes-Benz S-Class Sedan. Introduced for the 1980 model year, the 300 SD was built on the standard length wheelbase, and was fitted with Mercedes' OM617.951 diesel engine. This 3.0L turbodiesel inline five engine sent power through both manual or automatic transmissions to the rear wheels. Production of the Mercedes-Benz 300SD lasted until 1985, although the variant would continue life in the next generation W140 S-Class as the W140 Mercedes-Benz 300SD.