 The Mk.XIII became a big seller in 1965 when the SCCA created the Formula B category in America.The dominance of the Mk.XIII in Formula B was nearly absolute against its main rivals the Satta/Hruska-designed Alfa Romeo 105/115 DOHC unit, and the Alex von Falkenhausen-designed SOHC BMW M116 engine.This in turn allowed the now-viable engineering firm to reduce its previous near-total dependence on Lotus.