| 2003 IndyCar season | |
|---|---|
| IndyCar Series | |
| Season | |
| Races | 16 |
| Start date | March 2 |
| End date | October 17 |
| Awards | |
| Drivers' champion |  Scott Dixon |
| Manufacturers' Cup |  Toyota |
| Rookie of the Year |  Dan Wheldon |
| Indianapolis 500 winner |  Gil de Ferran |
The 2003 IRL IndyCar Series brought some of the biggest changes in its history. The league adopted the name IndyCar Series, after a settlement with CART prohibiting its use had expired. Several former CART teams brought their full operations to the IRL, most notably major squads Chip Ganassi Racing and Andretti Green Racing, as well as former CART engine manufacturers Toyota and Honda, replacing Infiniti who shifted its efforts to the new feeder series Infiniti Pro Series. Many of the IRL's old guard including Robbie Buhl, Greg Ray, and Buddy Lazier had difficulty competing in this new manufacturer-driven landscape. The league also added its first international race this year, taking over the CART date at Twin Ring Motegi.
The season's most successful entrants were Ganassi and Team Penske that had made the switch already the year before. New Zealander Scott Dixon won the opening race of the season at Homestead and ran very consistently all year long to win his first title at the age of 23. Gil de Ferran won Penske's third consecutive Indianapolis 500 in May and finished second to Dixon in the title race. The finale however was marred by a severe incident that nearly killed former series' champion and Indy 500 winner Kenny Bräck. De Ferran won the race with Dixon in second being well enough to seal the title. Bräck would eventually recover; however, Tony Renna, a Ganassi development driver, lost his life in a test crash at Indianapolis after the season had officially ended.
2003 was also the first and only engine title for Toyota and also first Asian and Japanese car manufacturer to won IndyCar Series IRL-era engine manufacturer's title and thus ending seven-year American engine manufacturer's supremacy. As of 2024, 2003 was also the last chassis manufacturer title victory for G-Force Technologies to date.