| 2005 IndyCar season | |
|---|---|
| IndyCar Series | |
| Season | |
| Races | 17 |
| Start date | March 6 |
| End date | October 16 |
| Awards | |
| Drivers' champion |  Dan Wheldon |
| Manufacturers' Cup |  Honda |
| Rookie of the Year |  Danica Patrick |
| Indianapolis 500 winner | Dan Wheldon |
The 2005 IRL IndyCar Series began on Sunday, March 6 and ended on Sunday, October 16. The season, which consisted of 17 races, was the 10th season of the IRL IndyCar Series since it split from CART in 1995.
Dan Wheldon was the dominant driver in the series in 2005, winning six races, including the 89th running of the Indianapolis 500, setting the record for most victories in an IRL season. However, the big story of the season was that of Rahal Letterman Racing's Danica Patrick, the fourth woman to compete in the Indy 500 and the first to lead a lap. She would eventually wind up in fourth. Danica's presence was a boost to the IRL's television ratings. The Indy 500's ratings were up 40% from the year before and subsequent races also saw a boost in ratings. Dan Wheldon was also became the first IndyCar driver to won the Indianapolis 500 and IndyCar Series overall driver's title respectively in the same season since Jacques Villeneuve in 1995 PPG IndyCar World Series season and also first ever in the Indy Racing League era.
The season was the first ever to introduce road courses and street circuits when the series held races at the Streets of St. Petersburg, Infineon Raceway and Watkins Glen International, where the series was previously known to have held events exclusively on oval tracks. Wheldon also became the series' first road/street course winner when he won in St. Petersburg.
The season was also the last for Chevrolet in the series, who confirmed in August that they would not return to the IRL (Chevrolet returned in 2012). At the start of the season, only Panther Racing's Tomas Scheckter and Tomáš Enge raced Chevrolet powered cars (although A. J. Foyt IV also started racing for Chevy beginning with the AMBER Alert Portal Indy 300 at Kentucky). The manufacturer situation within the IRL was the hot issue during the second half of the season and continued into the off-season. Toyota announced that they would leave the series shortly after the 2005 season ended, leaving Honda as the only remaining manufacturer in the IRL. Honda extended their engine supply contract through 2009 despite expressly saying that they did not wish to be the IRL's only supplier. The IRL announced that they extended their chassis supply contract with Panoz and Dallara through 2006.