The ninth year of IROC competition took place in 1985. IROC IX saw the use of the Chevrolet Camaro in all races, and continued the format introduced in IROC VIII. Race one took place on the Daytona International Speedway, race two took place at Mid-Ohio, race three was rained out at Talladega Superspeedway, and race four concluded the year at Michigan International Speedway. Harry Gant won the championship in a tie-breaker with Darrell Waltrip, and took home $158,200 for his efforts.
The roster of drivers and final points standings were as follows:
| Position | Driver | Points | Winnings | Series |
|---|---|---|---|---|
| 1 | Harry Gant1 | 45 | $158,200 | NASCAR Winston Cup |
| 2 | Darrell Waltrip1 | 45 | $80,400 | NASCAR Winston Cup |
| 3 | Bobby Rahal | 40 | $55,100 | CART |
| 4 | Tom Sneva | 32 | $43,000 | CART |
| 5 | Terry Labonte2 | 31 | $39,300 | NASCAR Winston Cup |
| 6 | Derek Bell2 | 31 | $30,000 | World Endurance Championship |
| 7 | John Watson | 30 | $29,000 | Formula One |
| 8 | Cale Yarborough | 29 | $27,400 | NASCAR Winston Cup |
| 9 | A. J. Foyt | 28 | $29,500 | CART |
| 10 | Jochen Mass | 27 | $23,000 | World Endurance Championship |
| 11 | Mario Andretti3 | 25 | $26,700 | CART |
| 12 | Tom Gloy | 13 | $20,000 | SCCA |