PORSCHE RACING HISTORYCees Siewertsen (NL)
1976 : Zandvoort International Group 2, 4 and 5 - 2nd overall
29 August 1976 - Zandvoort International Group 2, 4 and 5 - Non Championship Race
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 70 | Porsche 934 | 930 670 0540 | +2000 | Cees Siewertsen (NL) | Porsche Kannacher Krefeld/Wildcat Jeans (D) | 2nd | 2nd | 13 laps |