That word "diesel" you see at every gas station? Few people realize it was once a man's surname. In the late 19th century, the German engineer Rudolf Diesel invented a new engine far more efficient than the gasoline engines of his day. By compressing fuel to a high temperature and igniting it, his design produced great power from little fuel, and it soon became the beating heart of trucks, ships, and trains. People named both this revolutionary engine and the fuel it ran on after its inventor — diesel. Every time we fill up with diesel, we are, in a sense, speaking the name of a 19th-century inventor.