| 2004 IndyCar season | |
|---|---|
| IndyCar Series | |
| Season | |
| Races | 16 |
| Start date | February 29 |
| End date | October 17 |
| Awards | |
| Drivers' champion |  Tony Kanaan |
| Manufacturers' Cup |  Honda |
| Rookie of the Year | Kosuke Matsuura |
| Indianapolis 500 winner |  Buddy Rice |
The 2004 IRL IndyCar Series was dominated by two teams, Andretti Green Racing and Rahal Letterman Racing. While there was great parity in 2003 between Honda and Toyota powered teams, in 2004 Honda began to outshine Toyota bringing their teams Penske Racing and Chip Ganassi Racing down with it, leaving Scott Dixon winless and in 10th place in his attempt to defend his 2003 championship.
Season champion Tony Kanaan set a record by completing all 3,305 possible laps, the first IndyCar driver in modern history to do so.
This season was the last to feature an all oval tracks schedule, which was part of the concept that led to the creation of the Indy Racing League. By 2005, road and street courses started to appear in the schedule by a mainstream scheduling method, and by 2015, there were more races run on road/street courses than on oval tracks.