PORSCHE RACING HISTORYWilliam Vollery (CH)
1973
13 May 1973 - Euro GT GP Paris - European Championship for Grand Touring Cars
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 6 | Porsche 911 Carrera RSR | GT3.0 | William Vollery (CH) | Club Porsche Romand | 8th | 8th | 74 laps |
2 June 1973 - European GT Championship Imola - European Championship for Grand Touring Cars
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 93 | Porsche 911 Carrera RSR | GT3.0 | William Vollery (CH) | 8th | 7th | 38 laps |
24 June 1973 - Euro GT Nivelles - European Championship for Grand Touring Cars
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 28 | Porsche 911 Carrera RSR | GT3.0 | William Vollery (CH) | Porsche Club Romand (CH) | 7th | 7th | 50 laps |
5 August 1973 - Euro GT Thruxton - European Championship for Grand Touring Cars
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| Porsche 911 Carrera RS | GT3.0 | William Vollery (CH) | 7th | 7th |
2 September 1973 - Monza 6 Hours - European Championship for Grand Touring Cars
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 37 | Porsche 911 Carrera RSR | GT3.0 | Peter Zbinden (CH)/William Vollery (CH) | Porsche Club Romand | 7th | 6th | 15th | -19 laps |