Rudolf Christian Karl Diesel (1858–1913) was a German inventor and engineer, famous for the invention of the diesel engine, also called the compression-ignition engine. Realising that the steam engine was extremely inefficient, with as much as 90% of the fuel energy wasted, Diesel set about building an engine that had a much higher efficiency. Diesel engines are now widely used in ships, submarines, locomotives, lorries, buses and cars.

Diesel engine

In his first internal combustion engine, designed and built in 1893, the fuel was ignited by the high temperature resulting from its compression (a petrol engine, by contrast, uses a spark plug to ignite a air-fuel mixture). Diesel tested the first model to run on its own power later that year, and spent the next four years perfecting it. His first successful engine came into operation in 1897. Having patented his design in previous years, Diesel quickly became a millionaire.