In 1891, Panhard & Levassor built a batch of four identical cars, followed by series after series of increasing numbers, which, chronologically, makes Panhard-Levassor the world’s first make of car in continuous production. Although Benz and Daimler had built automobiles earlier, they were isolated examples and not part of any sustained program. Early in 1909, Rene de Knyff met with Hippolyte Panhard to tell him of his experience of driving the new Daimler with the knight sleeve-valve engine. He was enchanted with the silence and smoothness and urged the chairman to obtain a license and start mounting sleeve-valve engines in Panhard-Levassor cars. The head of the experimental department was impressed and supported the idea, and the first sleeve-valve engine design (a 20cv 4398cc, 4 cylinder model) went into production in 1910.