Speed to Spare(1937)

The champion race car driver Tommy Morton is the eternal rival to less-ethical speed king Larry 'Skids' Brannigan. What no one knows is that Tommy and Skids are actually brothers, separated at birth. Driven by a filial devotion that he can't explain, Tommy tries to dissuade Skids from recklessness, only to be "repaid" when Skids tries to steal away Tommy's blond girl-friend Eileen Hart.