Before World War I, the company used De Dion two- and four-cylinder engines in cars that ranged from 1032 cc to 9081 cc; beginning in 1902 (the year Edmund Rumpler became technical director),[1] they used their own engines as well. These cars, driven by Erwin Kleyer and Otto Kleyer (sons of the company founder Heinrich Kleyer) and by Alfred Theves won many sporting events. In the 1920s, Karl Irion raced many Adlers; popular models of the period included the 2298 cc, 1550 cc, and 4700 cc four-cylinders and the 2580 cc six-cylinders.