The first Cadillac automobiles were the 1903 Model built in the last quarter, 1902. These were 2-seater "horseless carriages" powered by a reliable and sturdy 10 hp (7 kW) single-cylinder engine developed by Henry Martyn Leland and built by Leland and Faulconer Manufacturing Company of Detroit, of which Henry Leland was founder, vice-president and general manager.
https://en.wikipedia.org/wiki/Cadillac_Runabout_and_Tonneau