In mid-2003, Cosworth provided the 3.5 L V8 XG badged as a Chevrolet Gen 4 engine to IRL IndyCar Series teams after the proprietary Chevrolet Gen 3 engine proved inadequate against rival Hondas and Toyotas during the 2003 season. While many teams left Chevrolet after the 2003 season, those that stayed saw a significant improvement in performance with the new "Chevworth" engine compared to their previous units. The XG finished second in its first race at Michigan on July 27, 2003. Sam Hornish, Jr. went on to win 3 races that season with the new XG. The XG was reduced in size to 3 L for 2004 season and it won one race in 2005 during Chevrolet's final season in IRL.