 Complete the following phrase:  For a period after the war, the Panhard-based Monopole racing cars received unofficial support from Panhard as did DB and other clients such as Robert Chancel, using it to good effect in winning the Index of Performance class at Le Mans in 1950, 1951, and 1952. In 1953, Panhard moved on to a more direct involvement with Chancel, which however came to an end after the deadly 