1899 as shortened form of automobile (q.v.). Similar evolution yielded French, German auto.
Entries linking to auto
automobile adj.
"self-moving, self-movable," 1883, in reference to electric traction cars, from French automobile (adj.), 1861, a hybrid from Greek autos "self" (see auto-) + French mobile "moving," from Latin mobilis "movable" (see mobile (adj.)).
autobahn n.
"German expressway," 1937, from German Autobahn (1930s), from auto "motor car, automobile" (short for automobil; see auto) + bahn "path, road," from Middle High German ban, bane "way, road," literally "strike" (as a swath cut through), from PIE *gwhen- "to strike, kill" (see bane).