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The BMW 507 was conceived by US automobile importer Max Hoffman who, in 1954, persuaded the BMW management to produce a roadster version of the BMW 501 and BMW 502 saloons to fill the gap between the expensive Mercedes-Benz 300SL and the cheap and underpowered Triumph and MG sports cars.Existing designs by Ernst Loof were rejected by Hoffman, who found them to be unappealing.
In November 1954, at Hoffman’s insistence, BMW contracted designer Albrecht von Goertz to design the BMW 503 and the 507.BMW engineer Fritz Fiedler was assigned to design the mechanical package, using existing components wherever possible.
Reference: wikipedia.org