Complex sentence: By 1960, he was a well-known race car driver ("Sports Illustrated" SCCA Driver of the Year), winning prestigious races until 1965, when he retired as a driver, to concentrate on his first Chevrolet dealership in Philadelphia, PA.
Split into simpler sentences: By 1960, he was a well-known race car driver ("Sports Illustrated" SCCA Driver of the Year). Penske continued racing until 1965, when he retired as a driver, to concentrate on his first Chevrolet dealership in Philadelphia, PA.