Chicago Auto Club Trophy Race
Elgin Road Race Course
8.384 Mile Road Course
36 Laps/300.456 Miles
August 20, 1915
| Finish | Start | Driver | Car # | Sponsor/Name | Chassis | Engine | Laps | Status |
Points |
| 1 | X | Earl Cooper | 8 | Stutz | Stutz | Stutz | 36 | 4:01:32 74.979 | 600* |
| 2 | X | Gil Andersen | 6 | Stutz | Stutz | Stutz | 36 | 4:05:04 73.859 | 320* |
| 3 | X | Barney Oldfield | 11 | Delage | Delage | Delage | 36 | 4:09:55 72.467 | 170* |
| 4 | X | Tom Alley | 10 | Ogren | Duesenberg | Duesenberg | 36 | 4:14:29 71.163 | 90* |
| 5 | X | Eddie O'Donnell | 7 | Duesenberg | Duesenberg | Duesenberg | 36 | 4:15:40 70.836 | 55* |
| 6 | X | W. W. Brown | 3 | DuChesneau | DuChesneau | Brown | 25 | Broken connecting rod | |
| 7 | X | Pete Henderson | 5 | Duesenberg | Duesenberg | Duesenberg | 22 | Out | |
| 8 | X | Ralph DePalma | 4 | Mercedes | Mercedes | Mercedes | 21 | Broken rocker arm | |
| 9 | X | Frank Justen | 2 | Cornelian | Cornelian | Cornelian | 11 | Broken water line | |
| -- | -- | Caleb Bragg | X | Stutz | Stutz | Stutz | -- | Withdrew | |
| -- | -- | George Patrick | X | Mercer | Mercer | Mercer | -- | Withdrew |
Known riding mechanics in this race:
| Finish | Start | Driver | Mechanic | Car # | Sponsor/Name | Chassis | Engine | Laps | Status |
| 3 | X | Barney Oldfield | Ray Daschbach | 11 | Delage | Delage | Delage | 36 | 4:09:55 72.467 |
| 9 | X | Frank Justen | William Justen | 2 | Cornelian | Cornelian | Cornelian | 11 | Broken water line |
| Lap Leaders | Total | Laps |
| Earl Cooper | 26 | 5-19, 26-36 |
| Gil Andersen | 6 | 20-25 |
| Ralph DePalma | 4 | 1-4 |