| 1984 · 1984 24 Hours of Le Mans | 5 | 12 | Gr.C1 | Schornstein Racing Team NewMan Joest Racing | Volkert Merl · "John Winter" (Louis Krages)Dieter Schornstein Volkert Merl "John Winter" (Louis Krages) | Porsche 956 | Porsche 935/79 2.6L F6 twin turbo | 340 | Wikipedia contributors · CC BY-SA 4.0 |
| 1984 · Trofeo Filippo Caracciolo, Monza | 6 | 12 | C1 | Schornstein Racing Team | Volkert Merl · Dieter Schornstein | Porsche 956 | — | 155 | WSPR historical record |
| 1984 · Grand Prix International 1000 Kilometres, Silverstone | 9 | 12 | 9. C1 | Schornstein Racing Team | Dieter Schornstein · Volkert Merl · "John Winter" | Porsche 956 | — | 198 | WSPR historical record |
| 1984 · ADAC 1000 Kilometres, Nürburgring | 10 | 12 | 0. C1 | D. S. Porsche Racing Team | Volkert Merl · "John Winter" · Dieter Schornstein | Porsche 956 | — | 194 | WSPR historical record |
| 1984 · British Aerospace 1000 Kilometres, Brands Hatch | 9 | 12 | 9. C1 | Schornstein Racing Team | Volkert Merl · Dieter Schornstein · "John Winter" | Porsche 956 | — | 217 | WSPR historical record |
| 1983 · 1983 24 Hours of Le Mans | 4 | 12 | Gr.C | Sorga Joest Racing | Volkert Merl · Mauricio de NarváezVolkert Merl Clemens Schickentanz Mauricio de Narváez | Porsche 956 | Porsche 935/79 2.6L F6 twin turbo | 362 | Wikipedia contributors · CC BY-SA 4.0 |
| 1983 · Grand Prix International 1000 Kilometres, Silverstone | retired | 12 | C | Joest Racing | Hans Heyer · Clemens Schickentanz · Volkert Merl | Porsche 956 | — | 74 | WSPR historical record |
| 1983 · Trophee Diners Club 1000 Kilometres, Spa-Francorchamps | retired | 12 | C | Joest Racing | Hans Heyer · Volkert Merl · Bob Wollek | Porsche 956 | — | 90 | WSPR historical record |
| 1983 · Mount Fuji 1000 Kilometres | 5 | 12 | 5. C | Joest Racing | Bob Wollek · Hans Heyer · Volkert Merl | Porsche 956 | — | 209 | WSPR historical record |
| 1982 · Trofeo Filippo Caracciolo, Monza | 4 | 86 | 2. Gr.5 | Vegla Racing Team | Volkert Merl · Dieter Schornstein · DNS - Bob Wollek | Porsche 935J | — | 167 | WSPR historical record |
| 1982 · Trofeo Banca Toscana 1000 kilometres, Mugello | 6 | 2 | 1. Gr.5 | Vegla Racing Team | Dieter Schornstein · Volkert Merl · Bob Wollek | Porsche 935J | — | 175 | WSPR historical record |
| 1981 · 20th Annual 24 Hour Pepsi Challenge Camel GT race, Daytona Internati onal Speedway | 59 | 6 | 0. GTX | Joest Racing | Volkert Merl · Jochen Mass · DNS - Reinhold Jöst | Porsche 935J Turbo | — | 59 | WSPR historical record |
| 1981 · Silverstone 6 Hours | retired | 5 | S+2.0 | Joest Racing | Jochen Mass · Reinhold Jöst · Volkert Merl | Porsche 908/80 | — | 0 | WSPR historical record |
| 1981 · Silverstone 6 Hours | entry_only | 6 | S+2.0 | Joest Racing | Volkert Merl · Jürgen Barth | Porsche 908/4 Turbo | — | | WSPR historical record |
| 1981 · 1000 km Nürburgring | 6 | 2 | 2. S+2.0 | Joest Racing | Volkert Merl · Jürgen Barth | Porsche 908/4 Turbo | — | 16 | WSPR historical record |
| 1980 · 1980 24 Hours of Le Mans | DNF | 46 | Gr.5 SP 2.0+ | Meccarillos Racing | Claude Haldi · Bernard Béguin · Volkert MerlClaude Haldi Bernard Béguin Volkert Merl | Porsche 935-K3/80 | Porsche 930 2.9L F6 turbo | 37 | Wikipedia contributors · CC BY-SA 4.0 |
| 1980 · 19th Annual 24 Hour Pepsi Challenge, Daytona International Speedweay | 1 | 2 | 1. GTX | LM Jöst Racing | Reinhold Jöst · Rolf Stommelen · Volkert Merl | Porsche 935J T | — | 715 | WSPR historical record |
| 1980 · Brands Hatch 6 Hours | retired | 1 | 3. S+2.0 | LM Jöst Racing | Reinhold Jöst · Volkert Merl | Porsche 908/4 Turbo | — | 111 | WSPR historical record |
| 1980 · Nürburgring 1000 Kilometres | retired | 33 | S+2.0 | Siegfried Brunn | Volkert Merl · Siegfried Brunn | Porsche 908/3 | — | 14 | WSPR historical record |
| 1980 · 6 hours of Watkins Glen | 5 | 4 | 5. Gr.5 | Dick Barbour Racing | Jürgen Barth · Volkert Merl | Porsche | — | 133 | WSPR historical record |
| 1979 · 18th Annual 24 Hour Pepsi Challenge, Daytona International Speedway | 46 | 4 | 1. GTX | LM Joest Porsche | Reinhold Jöst · Rolf Stommelen · Volkert Merl | Porsche 935J T | — | 162 | WSPR historical record |
| 1979 · Dijon 6 Hours | 1 | 31 | 1. S+2.0 | LM Joest Racing | Reinhold Jöst · Volkert Merl · Mario Ketterer | Porsche 908/3 | — | 255 | WSPR historical record |
| 1979 · 25th 1000 km Nürburgring | 5 | 1 | 5. Gr.5 | Liqui Moly Joest Racing | Volkert Merl · Derek Bell · Rolf Stommelen | Porsche 935/77A | — | 41 | WSPR historical record |
| 1979 · Rivet Suply 6 hours, Brands Hatch | 1 | 1 | 1. S+2.0 | LM Joest Racing | Reinhold Jöst · Volkert Merl | Porsche 908/3 TC | — | 231 | WSPR historical record |
| 1979 · Trofeo Ignazio Giunti, Vallelunga | retired | 19 | S+2.0 | Joest Racing | Reinhold Jöst · Mario Casoni · Volkert Merl | Porsche 908/3 Turbo | — | 65 | WSPR historical record |
| 1978 · 1978 24 Hours of Le Mans | DNA | 42 | Gr.5 SP | Konrad Racing | Franz Konrad · Volkert MerlFranz Konrad Volkert Merl | Porsche 935-77 | Porsche 3.0L F6 turbo | | Wikipedia contributors · CC BY-SA 4.0 |
| 1978 · 17th Annual 24 Hours of Daytona Camel GT Challenge | 13 | 21 | 8. GTX | Konrad Racing | Franz Konrad · Reinhold Jöst · Volkert Merl | Porsche 935/77 | — | 590 | WSPR historical record |
| 1978 · 6 h Mugello | 2 | 15 | 2. Gr.5 | Konrad Racing | Franz Konrad · Reinhold Jöst · Volkert Merl | Porsche 935/77 | — | 175 | WSPR historical record |
| 1978 · 6 h Dijon | retired | 8 | Gr.5 | Konrad Racing | Franz Konrad · Volkert Merl | Porsche 935/77 | — | 30 | WSPR historical record |
| 1978 · 6 h Silverstone | 6 | 12 | 6. Gr.5 | Konrad Racing | Franz Konrad · Volkert Merl | Porsche 935/77 | — | 203 | WSPR historical record |
| 1978 · 6 h Silverstone | did_not_start | 11 | Gr.5 | Konrad Racing | Franz Konrad · Volkert Merl | Porsche 935 | — | | WSPR historical record |
| 1978 · 1000 km Nürburgring | 4 | 12 | 4. Gr.5 | Konrad Racing | Volkert Merl · Ralf-Dieter Schreiber · Franz Konrad | Porsche 935/7 | — | 44 | WSPR historical record |
| 1978 · 1000 km Nürburgring | 8 | 11 | 8. Gr.5 | Konrad Racing | Franz Konrad · Volkert Merl · Clemens Schickentanz | Porsche 935/7 | — | 42 | WSPR historical record |
| 1978 · Misano 6 Hours | 3 | 12 | 3. Gr.5 | Konrad Racing | Franz Konrad · Volkert Merl | Porsche 935/77 | — | 255 | WSPR historical record |
| 1978 · 6 h Vallelunga | 7 | 19 | 7. Gr.5 | Konrad Racing | Franz Konrad · Volkert Merl | Porsche 935/77 | — | 238 | WSPR historical record |
| 1977 · Rivet Supply 6 Hours, Brands Hatch | retired | 5 | Gr.5 | Porsche Kremer Racing | Volkert Merl · Peter Hähnlein | Porsche 935 | — | 36 | WSPR historical record |
| 1977 · Hessen Preis, Hockenheim | 5 | 16 | 5. Gr.5 | Porsche Kremer Racing | Volkert Merl · Peter Hähnlein · Franz Konrad | Porsche 935 | — | 153 | WSPR historical record |