| 2.2.2003 | 24 h Daytona | 03 | Mantis Plus | Toto Lassally | Marcos USA | DNA |
| 2.2.2003 | 24 h Daytona | 03 | Mantis Plus | Euser / Knook / Crevels / Van der Kolk | Marcos USA | 23rd |
| 2.2.2003 | 24 h Daytona | 04 | Mantis Plus | | Marcos USA | DNA |
| 2.2.2003 | 24 h Daytona | | Mantis Plus | | Marcos International | DNA |
| 2.2.2003 | 24 h Daytona | | Mantara LM600 Evo | Cor Euser | Marcos International | DNA |
| 1.3.2003 | 250 mile Homestead | 03 | Mantis Plus | Cor Euser | Marcos International | DNA |
| 6.4.2003 | British GT Donington | 21 | Mantis | Eagling / Shrimpton | Glenn Eagling Motorsport | DNS |
| 6.4.2003 | British GT Donington | 44 | Mantis | Edwards / Wyatt | ISL Motorsport | 9th |
| 13.4.2003 | Belcar Zolder NRF | 10 | Mantis | van de Voort / van der Meyden | Power Motorsports | DNF |
| 13.4.2003 | Belcar Zolder NRF | 17 | Mantara LM600 Evo | Buurman / Vosse | Buurman | DNF |
| 13.4.2003 | Belcar Zolder NRF | 18 | Mantis | Van Dongen / Noorman | Eurotech | 11th |
| 13.4.2003 | Belcar Zolder NRF | 19 | Mantis | De Groot / Van de Haterd | Eurotech | 7th |
| 20.4.2003 | British GT Snetterton | 21 | Mantis | Eagling / Shrimpton | Glenn Eagling Motorsport | DNF |
| 20.4.2003 | British GT Snetterton | 44 | Mantis | Edwards / Wyatt | ISL Motorsport | DNA |
| 27.4.2003 | Spanish GT Albacete | 2 | Mantara LM600 Evo | Saldaña / Monzón | Meycom Sport | 1st/1st |
| 27.4.2003 | Belcar Zolder WSN | 10 | Mantis | van de Voort / van der Meyden | Power Motorsports | DNA |
| 27.4.2003 | Belcar Zolder WSN | 17 | Mantara LM600 Evo | Buurman / Vosse | Buurman | DNA |
| 27.4.2003 | Belcar Zolder WSN | 18 | Mantis | Van Dongen / Noorman | Eurotech/Hadegro Racing | 13th |
| 27.4.2003 | Belcar Zolder WSN | 19 | Mantis | De Groot / Van de Haterd | Eurotech/Hadegro Racing | DNF |
| 27.4.2003 | Belcar Zolder WSN | 23 | Mantis | De Sterck / Moritz | Bert Moritz | DNF |
| 3.5.2003 | 250 mile Phoenix | 03 | Mantis Plus | Cor Euser | Marcos International | DNA |
| 4.5.2003 | Euro GT Nürburgring | 1 | Mantara LM600 Evo | Cor Euser | Team Marcos Racing International | DNF/1st |
| 4.5.2003 | Euro GT Nürburgring | 58 | Mantis | Arjan van der Zwaan | - | DNS/10th |
| 4.5.2003 | Euro GT Nürburgring | 61 | Mantis | Knook / Van der Kolk | Rob Knook | 4th/4th |
| 11.5.2003 | Belcar Spa Belpro | 10 | Mantis | van de Voort / van der Meyden | Power Motorsports | 12th |
| 11.5.2003 | Belcar Spa Belpro | 18 | Mantis | Van Dongen / Noorman | Eurotech-Hadegro Racing | DNF |
| 11.5.2003 | Belcar Spa Belpro | 19 | Mantis | De Groot / Van de Haterd | Eurotech-Hadegro Racing | 7th |
| 11.5.2003 | British GT Knockhill | 21 | Mantis | Eagling / Shrimpton | Glenn Eagling Motorsport | 8th |
| 11.5.2003 | Belcar Spa Belpro | 23 | Mantis | De Sterck / Moritz | Bert Moritz | 36th |
| 11.5.2003 | British GT Knockhill | 44 | Mantis | Edwards / Wyatt | ISL Motorsport | 13th |
| 18.5.2003 | Spanish GT Jarama | 2 | Mantara LM600 Evo | Saldaña / Monzón | Meycom Sport | 12th/DNF |
| 25.5.2003 | British GT Silverstone | 21 | Mantis | Eagling / Shrimpton | Glenn Eagling Motorsport | DNF |
| 25.5.2003 | British GT Silverstone | 44 | Mantis | Edwards / Wyatt | ISL Motorsport | 13th |
| 8.6.2003 | Belcar Spa SER | 10 | Mantis | van de Voort / van der Meyden | Power Motorsports | 15th |
| 8.6.2003 | Belcar Spa SER | 17 | Mantara LM600 Evo | Euser / Huisman | Buurman | DNF |
| 8.6.2003 | Belcar Spa SER | 18 | Mantis | Van Dongen / Noorman / Ritsma | Eurotech-Hadegro Racing | 21st |
| 8.6.2003 | Belcar Spa SER | 19 | Mantis | De Groot / Van de Haterd | Eurotech-Hadegro Racing | 8th |
| 8.6.2003 | Belcar Spa SER | 23 | Mantis | De Sterck / Moritz | Bert Moritz | 32nd |
| 22.6.2003 | British GT Castle Combe | 8 | Mantara LM600 | Taylor / Colwell | Taylors Foundry Motorsport | DNF |
| 22.6.2003 | British GT Castle Combe | 21 | Mantis | Eagling / Shrimpton | Glenn Eagling Motorsport | 5th |
| 22.6.2003 | British GT Castle Combe | 44 | Mantis | Edwards / Wyatt | ISL Motorsport | 12th |
| 29.6.2003 | Euro GT A1-Ring | 1 | Mantara LM600 Evo | Cor Euser | Team Marcos Racing International | DNF/1st |
| 29.6.2003 | Euro GT A1-Ring | 56 | Mantis | Carl Krieger | Team Marcos Racing International | 11th/12th |
| 29.6.2003 | Euro GT A1-Ring | 81 | Mantis | Knook / Van der Kolk | Team Knook/H&P | 5th/8th |
| 6.7.2003 | Spanish GT Estoril | 2 | Mantara LM600 Evo | Saldaña / Monzón | Meycom Sport | DNS |
| 6.7.2003 | Spanish GT Estoril | 19 | Mantara LM600 Evo | Euser / Amorim | Marcos Racing Internacional | DQ/DNS |
| 6.7.2003 | Spanish GT Estoril | 34 | Mantis | Carlos Rodriguez | Marcos Racing Internacional | DNF/DNS |
| 13.7.2003 | British GT Oulton Park | 21 | Mantis | Eagling / Shrimpton | Glenn Eagling Motorsport | DNF |
| 13.7.2003 | British GT Oulton Park | 44 | Mantis | Edwards / Wyatt | ISL Motorsport | 8th |
| 3.8.2003 | British GT Rockingham | 21 | Mantis | Daniel Eagling | Glenn Eagling Motorsport | DNF |
| 3.8.2003 | British GT Rockingham | 44 | Mantis | Edwards / Wyatt | ISL Motorsport | 13th |
| 17.8.2003 | British GT Thruxton | 21 | Mantis | Daniel Eagling | Glenn Eagling Motorsport | DNF |
| 17.8.2003 | British GT Thruxton | 44 | Mantis | Edwards / Turvey | ISL Motorsport | DNS |
| 24.8.2003 | Euro GT Spa | 1 | Mantara LM600 Evo | Cor Euser | Team Marcos Racing International | DNF/DNS |
| 24.8.2003 | 24 h Zolder | 19 | Mantis | De Groot / Van de Haterd / Van Dongen | Eurotech-Hadegro Racing | 12th |
| 24.8.2003 | 24 h Zolder | 23 | Mantis | De Sterck / Moritz / Brom / Kitsz | Bert Moritz | 24th |
| 24.8.2003 | Euro GT Spa | 56 | Mantis | | Team Marcos Racing International | - |
| 24.8.2003 | Euro GT Spa | 81 | Mantis | Van der Kolk / Knook | Team Knook/H&P | 3rd/3rd |
| 31.8.2003 | 1000 km Spa | 8 | Mantara LM600 | Taylor / Colwell | Taylors Foundry Motorsport | DNA |
| 31.8.2003 | 1000 km Spa | 21 | Mantis | Eagling / Shrimpton | Glenn Eagling Motorsport | DNA |
| 31.8.2003 | 1000 km Spa | 130 | Mantara LM600 Evo | Euser / Lockie / Menten | Cor Euser | DNF |
| 31.8.2003 | 1000 km Spa | 144 | Mantis | Turvey / Bonner / Edwards | Alun Edwards | DNF |
| 14.9.2003 | Spanish GT Valencia | 19 | Mantara LM600 Evo | Euser / Amorim | Marcos Racing Internacional | 4th/9th |
| 14.9.2003 | Spanish GT Valencia | 34 | Mantis | Saez-Merino / Krieger | Marcos Racing Internacional | DNF/10th |
| 21.9.2003 | Belcar Spa RF | 10 | Mantis | van de Voort / van der Meyden | Power Motorsports | 18th |
| 21.9.2003 | Belcar Spa RF | 17 | Mantara LM600 Evo | Buurman / Buurman | Buurman | DNA |
| 21.9.2003 | Belcar Spa RF | 18 | Mantis | Euser / Van Dongen | Eurotech/Hadegro Racing | 7th |
| 21.9.2003 | Belcar Spa RF | 19 | Mantis | De Groot / Van de Haterd | Eurotech/Hadegro Racing | 8th |
| 21.9.2003 | Belcar Spa RF | 23 | Mantis | De Sterck / Moritz | Bert Moritz | 20th |
| 28.9.2003 | British GT Brands Hatch | 8 | Mantara LM600 | Taylor / Stephens | Taylors Foundry Motorsport | DNS |
| 28.9.2003 | British GT Brands Hatch | 21 | Mantis | Eagling / Eagling | Glenn Eagling Motorsport | 4th |
| 28.9.2003 | British GT Brands Hatch | 44 | Mantis | Edwards / Bonner | ISL Motorsport | DNF |
| 12.10.2003 | Spanish GT Jerez | 5 | Mantara LM600 Evo | Mello-Breyner / Mello-Breyner | Team Galp Formula | 18th/4th |
| 12.10.2003 | Spanish GT Jerez | 19 | Mantara LM600 Evo | Euser / Bastos | Marcos Racing Internacional | 3rd/DNF |
| 12.10.2003 | Spanish GT Jerez | 34 | Mantis | Saez-Merino / Van der Kolk | Marcos Racing Internacional | 11th/13th |
| 19.10.2003 | Belcar Zolder BM | 17 | Mantara LM600 Evo | Buurman / Buurman | Buurman | DNA |
| 19.10.2003 | Belcar Zolder BM | 18 | Mantis | Euser / Van Dongen | Eurotech/Hadegro Racing | 6th |
| 19.10.2003 | Belcar Zolder BM | 19 | Mantis | De Groot / Van de Haterd | Eurotech/Hadegro Racing | 10th |
| 19.10.2003 | Belcar Zolder BM | 23 | Mantis | Moonens / De Sterck | Bert Moritz | 26th |
| 9.11.2003 | Spanish GT Barcelona | 2 | Mantara LM600 Evo | Mello-Breyner / Mello-Breyner | Team Galp Formula | 32nd |
| 9.11.2003 | Spanish GT Barcelona | 19 | Mantara LM600 Evo | Euser / Van der Kolk | Marcos Racing Internacional | 9th |
| 9.11.2003 | Spanish GT Barcelona | 34 | Mantis | Saez-Merino / van der Meyden | Marcos Racing Internacional | 34th |
| 9.11.2003 | Spanish GT Barcelona | 59 | Mantis | Krieger / Roelse | Marcos Racing Internacional | 37th |