Schuppan competed in three Indianapolis 500 races. These were 1976 (where he won the Rookie of the Year award), 1979 and 1981, with a best result of third in 1981 driving a McLaren-Ford. In all, he started 32 CART and USAC Championship races. He won the 1974 and 1976 Macau Grand Prix races, dominating the 1974 race, winning by four laps.