The twelfth year of IROC competition took place in 1988. IROC XII 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 Riverside International Raceway, race three ran at Michigan International Speedway, and race four concluded the year at Watkins Glen International. Al Unser, Jr. won his second championship, and took home $211,900 for his efforts.
The roster of drivers and final points standings were as follows:
| Position | Driver | Points | Winnings | Series |
|---|---|---|---|---|
| 1 | Al Unser, Jr. | 66 | $211,900 | CART |
| 2 | Terry Labonte | 55 | $95,000 | NASCAR Winston Cup |
| 3 | Scott Pruett | 51 | $72,900 | SCCA Trans-Am Series |
| 4 | Bill Elliott | 46 | $58,900 | NASCAR Winston Cup |
| 5 | Dale Earnhardt1 | 45 | $51,000 | NASCAR Winston Cup |
| 6 | Geoff Bodine1 | 45 | $49,500 | NASCAR Winston Cup |
| 7 | Al Holbert | 39 | $35,000 | IMSA Camel GT |
| 8 | Al Unser | 38 | $34,000 | CART |
| 9 | Chip Robinson | 36 | $38,000 | IMSA Camel GT |
| 10 | Chris Cord | 26 | $32,000 | IMSA Camel GT |
| 11 | Bobby Rahal | 24 | $31,000 | CART |
| 12 | Roberto Guerrero | 19 | $30,400 | CART |