hippomobile (n.)

before vowels, hipp-, word-forming element meaning "horse," from Greek hippo-, from hippos "horse," from PIE root *ekwo- "horse."

"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.)).