Which inventor created the first successful practical diesel engine in the 1890s?

Rudolf Diesel created the first successful practical diesel engine in the 1890s.

Diesel’s engine used compression ignition rather than a spark plug. Air was compressed until it became extremely hot, and fuel injected into that air ignited without a separate spark. Diesel proposed the principle in the 1890s as a way to achieve higher efficiency than contemporary steam engines and gasoline engines.

The first successful engine was built with Maschinenfabrik Augsburg, now part of MAN, and tested in 1897. It achieved much better efficiency than many engines of the era, although early diesel engines were large, heavy, and difficult to manufacture.

Nikolaus Otto developed the four-stroke petrol engine, not the diesel engine. Modern diesel engines may use turbochargers, electronic injection, and sophisticated emissions controls, but their defining combustion process still follows Diesel’s compression-ignition principle. Diesel died in 1913, before the engine became dominant in many transport and industrial applications.