In the 1920s, the cars used in endurance racing and Grand Prix were still basically identical, with fenders and two seats, to carry a mechanic if necessary or permitted.
Cars such as the Bugatti Type 35 were almost equally at home in Grands Prix and endurance events, but specialisation gradually started to differentiate the sports-racer from the Grand Prix car.
The legendary Alfa Romeo Tipo A Monoposto started the evolution of the true single-seater in the early 1930s; the Grand Prix racer and its miniature voiturette offspring rapidly evolved into high performance single seaters optimised for relatively short races, by dropping fenders and the second seat.
During the later 1930s, French constructors, unable to keep up with the progress of the Mercedes-Benz and Auto-Union cars in GP racing, withdrew into primarily domestic competition with large-capacity sports cars – marques such as Delahaye, Talbot and the later Bugattis were locally prominent.
Similarly, through the 1920s and 1930s the roadgoing sports/GT car started to emerge as distinct from fast tourers (Le Mans had originally been a race for touring cars) and sports cars, whether descended from primarily roadgoing vehicles or developed from pure-bred racing cars came to dominate races such as Le Mans and the Mille Miglia.
In open-road endurance races across Europe such as the Mille Miglia, Tour de France and Targa Florio, which were often run on dusty roads, the need for fenders and a mechanic or navigator was still there. As mainly Italian cars and races defined the genre, the category was called Gran Turismo, as long distances had to be travelled, rather than running around on short circuits only. Reliability and some basic comfort were necessary in order to endure the task.