1991 IndyCar season

The 1991 IndyCar season, the thirteenth in the CART era of U.S. open-wheel racing, consisted of 18 races, beginning in Surfers Paradise, Queensland, Australia on March 17 and concluding in Monterey, California on October 20. There was one non-championship event, the Marlboro Challenge. The PPG Indy Car World Series Drivers' Champion was Michael Andretti, the Indianapolis 500 & Marlboro 500 winner was Rick Mears. Rookie of the Year was Jeff Andretti. The 75th Indianapolis 500 was sanctioned by the USAC, but counted in the CART points standings.

Drivers and constructors
The following teams and drivers competed for the 1991 Indy Car World Series.

Races
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 * Indianapolis was USAC-sanctioned but counted towards the CART title.

Final driver standings
Point Scoring System:
 * Points are awarded based on each driver's resulting place (regardless of whether the car is running at the end of the race):

Bonus Points:
 * 1 For Pole Position
 * 1 For Leading The Most Laps Of The Race

Nation's Cup

 * Top result per race counts towards Nation's Cup.