An accomplished open wheel racer who made a single CART start in 1989, Harrington made a last second Bump Day run to qualify for the first IRL-sanctioned Indianapolis 500 in 1996. In 1999 he ran a full IRL season with his own team and had numerous top ten finishes, including a top five finish at Phoenix International Raceway, at the time the highest finishing position for the Infiniti engine. Despite failing to qualify for the Indy 500 and suffering serious injuries at Texas 1 (broken left tibia, right fibula, right foot and three ribs) he won the Rookie of the Year honors by a slim margin over Robby McGehee. Harrington attempted to qualify for seven different Indy 500 races but only succeeded once, in his second attempt in 1996. In 1998 he was well on his way to a top qualifying position when he suffered a blown engine that ended his month as the team had no backup. He had a best IRL finish of fourth at Phoenix in 1999 and had a total of 14 series starts, which is the fewest total starts by any IRL Rookie of the Year. Never being one to be short on speed, his bad luck at the Speedway was well known as he won the Jigger award for his bad luck. Harrington is also the only person to ever compete in Formula Atlantic, the original Indy Lights Series, the Infiniti Pro Series, the CART Indy Car Series and the IRL Indy Car Series.