Marco Andretti announced Wednesday that he has decided to end his career as a race car driver. The 38-year-old grandson of racing legend Mario Andretti has competed in 20 Indianapolis 500s. He nearly won during his rookie year in 2006 before Sam Hornish Jr. slipped past him in a photo finish. Marco Andretti also has three third-place finishes in the iconic race. "I am announcing my retirement from motor racing and the Indianapolis 500," he posted on social media. "That totals 20 starts at the