How 'bout Cadillac's, "Penalty of Leadership" in 1914? That one ad catapulted Cadillac into the front ranks of American luxury cars. Too bad they seemed to have forgotten it long ago at Cadillac.
Rolls-Royce had a good one, in early 20s I think. Picture of Henry Royce, quoted, "Strive for perfection in everything. Take the best and make it better. When it does not exist, design it. Accept nothing nearly right of good enough". He was plugging Rolls-Royces built in Springfield, MA, so I suppose this is sort of an American ad.