"Motorer" we have given our reasons for rejecting, and there only remains "motorist" or a compound like "motor-man" or "motor-driver." Mr. C.P.G. Scott, the etymologist of the Century Dictionary, strongly favors "motor-man" or "motor-driver," though he would not object to "motorist" and prefers it above any other single word.
["Electric Power," October 1889]
[motorist etymology, motorist origin, 英语词源]