 Competing in the United States, Wagner won the Vanderbilt Cup of 1906 driving a Darracq model 120 over a Long Island racecourse.He finished 5th in the 1907 Kaiserpreis in Germany but the following year in Savannah won the first ever United States Grand Prix driving a Fiat.Driving a Mercedes, Wagner finished second to Christian Lautenschlager in the 1914 French Grand Prix at Lyon.