Audi will pull out of the World Endurance Championship and end its 18-year involvement in the Le Mans 24 Hours at the conclusion of 2016.INSIGHT: What Audi meant to Le MansANALYSIS: What does Audi withdrawal mean for WEC?WEC: ACO takes veiled swipe at AudiGALLERY: 18 Years of Audi at Le...