When he was 22, he convinced his mother that he needed a Bugatti to get to the clients of his paper company faster. He actually used it for racing.
He was hired as a driver by a local Bugatti dealer, and in 1929 won the Grand Prix de Dieppe in a Type 35B. His real fame came when he beat the factory team driver Chiron in the 1930 Grand Prix de Monaco.
He was briefly with the Maserati team and later joined the Bugatti factory team. With them, he won the 1934 Grand Prix de Belgique, driving a Type 59.
For 1935, he drove for Scuderia Ferrari, alongside drivers like Nuvolari and Chiron. Dreyfus had one more major win before the war, racing a Delahaye to victory at the 1938 Grand Prix de Pau.
He went to the U.S. to race in the 1940 Indianapolis 500, finishing a creditable 10th place. It became impossible to return because of World War Two, so he stayed.
He enlisted in the United States Army during the war, and at the end of it became an American citizen. He opened the famous “Le Chanteclair” restaurant in New York City in 1953, which became a gathering place for the rich and famous, and for the racers coming to the city.
Dreyfus died in New York City in 1993.