2003 Australian Nations Cup Championship
The 2003 Australian Nations Cup Championship was a CAMS sanctioned motor racing title for drivers of GT sports cars complying with Group 2E Nations Cup regulations. The championship, which was managed by Procar Australia as part of the 2003 Procar Championship Series, was the fourth Australian Nations Cup Championship. The title was won by Paul Stokell driving a Lamborghini Diablo GTR.
Calendar
The championship was contested over an eight-round series with three races per round.| Round | Circuit | State | Date | Race Winners | Round winner | Car | Report |
| 1 | Adelaide Street Circuit | South Australia | 22–23 March | R1 - John Bowe R2 - John Bowe R3 - Paul Stokell | John Bowe | Ferrari 360 N-GT | |
| 2 | Symmons Plains | Tasmania | 26–27 April | R1 - John Bowe R2 - Nathan Pretty R3 - Paul Stokell | Nathan Pretty | Holden Monaro 427C | |
| 3 | Wakefield Park | New South Wales | 31 May - 1 June | R1 - John Bowe R2 - John Bowe R3 - John Bowe | John Bowe | Ferrari 360 N-GT | |
| 4 | Queensland Raceway | Queensland | 14–15 June | R1 - Paul Stokell R2 - Nathan Pretty R3 - Paul Stokell | Paul Stokell | Lamborghini Diablo GTR | |
| 5 | Oran Park | New South Wales | 12–13 July | R1 - Paul Stokell R2 - Paul Stokell R3 - Paul Stokell | Paul Stokell | Lamborghini Diablo GTR | |
| 6 | Phillip Island | Victoria | 9–10 August | R1 - Paul Stokell R2 - Nathan Pretty R3 - Paul Stokell | Paul Stokell | Lamborghini Diablo GTR | |
| 7 | Winton Motor Raceway | Victoria | 20–21 September | R1 - John Bowe R2 - Paul Stokell R3 - Nathan Pretty | Nathan Pretty | Holden Monaro 427C | |
| 8 | Surfers Paradise Street Circuit | Queensland | 23–26 October | R1 - Peter Brock R2 - Paul Stokell R3 - ** | Paul Stokell | Lamborghini Diablo GTR |
Note: ** Race 3 at the Surfers Paradise round was cancelled due to a security issue.
Points system
Championship points were awarded on a 30-20-16-13-11-10-9-8-7-6-5-4-3-2-1 basis to the first 15 finishers in each race.In addition, three points were awarded to the driver earning pole position.
Results
Manufacturers Trophy
The Manufacturers Trophy was awarded to the manufacturer which attained the highest number of cumulative points over all rounds, inclusive of pole position points. Points were awarded as per the drivers championship to the two highest scoring finishers from each marque in each race.| Position | Manufacturer | Car | Points |
| 1 |  Porsche | 911 GT3 911 GT3 RS 911 GT3 Cup 911 GT3 Carrera 911 GT3 Clubsport | 1,221 |
| 2 |  Lamborghini | Diablo GTR Diablo SVR | 945 |
| 3 | Ferrari | 360 N-GT 360 Modena Challenge | 901 |
| 4 |  Holden | Monaro 427C | 639 |
| 5 |  Chrysler | Viper ACR | 248 |
| 6 | Maserati | Trofeo | 201 |
| 7 | BMW | Z3 GT | 94 |
| 8 | Chevrolet | Corvette C5 | 41 |
| 9 | Ford | Mustang Cobra R | 25 |