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.

Top Ten Results On April 3, the Honda Grand Prix on the Streets of St. Petersburg (Florida) marked the first non-oval event for the IndyCar Series.

Top Ten Results On May 29, at the Indianapolis Motor Speedway, Dan Wheldon won his first Indy 500 and his fourth race of the season.

Top Ten Results On June 11, at Texas Motor Speedway, Tomas Scheckter won his first race of the season, sitting on the pole and leading for 119 of 200 laps.

Top Ten Results On July 3, at Kansas Speedway, Tony Kanaan won by a fraction of a second over Dan Wheldon and Vítor Meira.

Top Ten Results On July 31 at Michigan International Speedway, Bryan Herta won from the pole, leading 159 of 200 laps.

Top Ten Results On August 14 at Kentucky Speedway, Scott Sharp won for the first time since 2003 at Twin Ring Motegi, holding off Vítor Meira for the last laps to win.

Top Ten Results On August 21 at Pikes Peak International Raceway, Penske Racing teammates Hélio Castroneves and Sam Hornish Jr. started 1–2.

Ryan Briscoe sat on the pole, but caused a three-car accident on lap 20 that also eliminated Hélio Castroneves and Danica Patrick from the race.

Top Ten Results On September 11 at Chicagoland Speedway, Dan Wheldon won his sixth race, breaking the all-time record for most wins in an IRL season.

Top Ten Results On September 25 at Watkins Glen International, Scott Dixon won his first race since his 2003 IndyCar Series Championship season.