The 2006 IRL IndyCar Series season began on March 26 and concluded on September 10. Sam Hornish, Jr. won his third IndyCar Series championship. Hornish also won the 90th Indianapolis 500, passing rookie Marco Andretti on the final lap less than from the finish line. The title chase was very dramatic between Penske drivers Hornish and Hélio Castroneves battling Ganassi drivers Dan Wheldon and Scott Dixon. The four drivers occupied the first four positions in the final race at Chicagoland Speedway, with Wheldon leading Dixon home for a Ganassi 1-2 but Hornish finishing third, edging out reigning champion Wheldon on a tiebreak. Third would have been enough to catapult fourth-place finisher Castroneves to take the title, but he instead ended up two points behind Hornish and Wheldon. Dixon was also in strong title contention, finishing a mere 15 points adrift of the championship.