Ferrari began their bid for a third consecutive Le Mans 24 hours after former tennis champion Roger Federer waved the starter flag at the Sarthe circuit on Saturday.
Cadillac, who have never yet won at Le Mans, started the 93rd edition on the front row with two of its prototypes and held the early lead along with the Porsches.
BMW and Alpine are also expected to play a part in the most famous endurance race of all although Ferrari and Toyota have won the last seven editions between them.
Ferrari have also won the first three races of the World Endurance Championship (WEC) in Losail, Imola and Spa. Their two official cars, however, only qualified seventh and 11th at Le Mans.
The other teams, Peugeot and Aston Martin, are not expected to challenge.
A total of 62 cars are entered this weekend with 21 prototypes in the premier hypercar category.