Wheldon began competitive karting at the age of eight and achieved early success, before progressing to open-wheel car racing in the U.S. F2000 National Championship, the Toyota Atlantic Championship and Indy Lights. He began driving in IndyCar with Panther Racing in 2002. The following year, Wheldon moved to AGR, finishing as the runner-up in the 2004 series championship. He won the drivers' title in 2005 with the record for most victories (including the 2005 Indianapolis 500) during a season. In the 2006 season, he moved to CGR, tying Sam Hornish Jr. in points but finishing second because of count-back on the number of victories taken by both drivers. During the 2007 and 2008 seasons, Wheldon's form lowered but he won four additional races and placed fourth in points in both years.