2006 Indianapolis 500

The 90th Indianapolis 500 was an IndyCar Series motor race held on Sunday, May 28, 2006, at the Indianapolis Motor Speedway in Speedway, Indiana. It was the fourth round of the 2006 IndyCar Series season. The race was won by Sam Hornish Jr., who earned his first and only win at Indianapolis. The win marked the record-extending fourteenth Indianapolis 500 victory for Team Penske. Hornish was one of the pre-race favorites to win, after setting fast laps during practice sessions and winning the pole position. Hornish, a two-time Indy Racing League champion (2001, 2002) had never finished in the top ten at Indy in six previous starts. Hornish go on to the 2006 IndyCar Series championship (his third overall), becoming the second driver in a row to win the Indianapolis 500 and season championship in the same year.

The track opened for practice on May 9. Time trials were scheduled to be held on May 13–14 and May 20–21, however, the first two days were rained out. Pole qualifying was rescheduled for May 20, and Bump Day was held on May 21. Carb Day, the traditional final day of practice, was held on May 26, alongside the Pit Stop Challenge and the Freedom 100.

In one of the most dramatic finishes in Indy 500 history, 19-year old rookie Marco Andretti took the lead with three laps to go. Marco passed his father Michael Andretti on the outside of turn one. Michael Andretti, a veteran of 14 previous Indy starts, had come out retirement to race alongside his son. Marco Andretti battled Sam Hornish Jr. over the final two laps, holding off the challenge until the final straightaway. On the final lap, Hornish passed Marco Andretti about 450 feet from the finish line to take the win. It was the first time in the 90-year history of the event that a driver would successfully make a pass for the lead on the final lap en route to victory. Despite Andretti's loss, he was unanimously named Rookie of the Year. Michael Andretti, still winless as a driver at Indianapolis, came home third.

The margin of victory was 0.0635 seconds – just over one car-length – which was the second-closest finish in Indy 500 history at the time (as of 2025, it is the third-closest finish). Defending race winner Dan Wheldon dominated much of the race, leading a race-high 148 laps. However, a small tire puncture forced him to make his final pit stop earlier than planned, which coupled with an untimely caution period, saw him slip to fourth place at the finish.