 In 1972, with only Alfa answering the challenge, the 312 PB was very successful and won all World Sportscar Championship races in which it was entered.Ferrari skipped Le Mans, though, as the F1-based engine had not lasted 24 hours in testing and would surely spoil their otherwise perfect record.In 1973, Matra which had previously focused on Le Mans also challenged for the championship while Alfa was absent.