Summertime Killer(1972)

He can kill you standing still. Or at 200 M.P.H.

During his childhood, a boy sees four men drown his father; now, the grown young man makes it his business to kill each member of the foursome. His last killing presents him with some challenges, as his victim is only wounded. He kidnaps the man's daughter and goes to a hideout. In the meantime, an ex-cop has been tracking them down.