PORSCHE RACING HISTORYMark Altman (USA)
1985
14 April 1985 - Road Atlanta 500 km - IMSA - International Motor Sport Association
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 31 | Porsche 911 Carrera | GTO | Gary Altman (USA)/Mark Altman (USA) | Altman Bros. Motor Racing (USA) | 27th | 7th | 45th | 98 laps |
8 September 1985 - Pocono 500 km - IMSA - International Motor Sport Association
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 31 | Porsche 911 | GTU | Gary Altman (USA)/Mark Altman (USA) | Altman Bros. Motor Racing (USA) | 25th | 8th | 34th | 93 laps |
29 September 1985 - Watkins Glen 500 km - IMSA - International Motor Sport Association
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 31 | Porsche 911 | GTU | Gary Altman (USA)/Mark Altman (USA) | Altman Bros. Motor Racing (USA) | 23rd | 5th | 43rd | 75 laps |
5 October 1985 - Columbus IMSA GT - IMSA - International Motor Sport Association
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 31 | Porsche 911 | GTU | Mark Altman (USA) | Altman Bros Motor Racing (USA) | 14th | 6th | 25th | 33 laps |