Complex sentence: Apart from four hours at Le Rosey, Onassis had no formal schooling nor did he have friends of his own age, and, despite not being gifted academically, he was very knowledgeable about automobiles and motors, which impressed Gianni Agnelli from Fiat.
Split into simpler sentences: Apart from four hours at Le Rosey, Onassis had no formal schooling nor did he have friends of his own age. Despite not being gifted academically, he was very knowledgeable about automobiles and motors, which impressed Gianni Agnelli from Fiat.