| 00 | Thomasson / Zitza / Lewis, Jr. / Wheeler | TZ Motorsports | James Thomason | Porsche | 996 GT3 Cup | | Porsche | GT |
| 01 | Pruett / Diaz / Papis | CompUSA Chip Ganassi with Felix Sabates (USA) | Mike Hull | Riley | Mk XI | | Lexus | DP |
| 02 | Dixon / Wheldon / Mears | Target Chip Ganassi with Felix Sabates (USA) | Mike Hull | Riley | Mk XI | | Lexus | DP |
| 05 | Alhadeff / Auberlen / Milner / Marks | Sigalsport BMW | Gene Sigal | BMW | M3 | E46 | BMW | GT |
| 06 | Reese / Archer / Oasis / Crescentini | Banner Racing (USA) | Leighton Reese | Chevrolet | Corvette | | Chevrolet | GT |
| 08 | Goldin / Goldin / Finlay | Goldin Brothers Racing (USA) | Steve Goldin | Mazda | RX-8 | | Mazda | GT |
| 2 | Wallace / Patrick | Howard - Boss Motorsports | Maxwell Crawford | Crawford | DP03 | | Pontiac | DP |
| 3 | Lewis / LaJoie | Southard Motorsports | Steve Southard | Riley | Mk XI | | BMW | DP |
| 4 | Wallace / Leitzinger / Stewart | Howard - Boss Motorsports | Maxwell Crawford | Crawford | DP03 | | Pontiac | DP |
| 5 | Dayton / Knoop / DeVries / Matthews | Essex Racing | Michael Gue | Crawford | DP03 | | Ford | DP |
| 6 | Wilden / Mears, Jr. / Borkowski / Tracy | Graydon Elliot Fusion Racing with MSR | Michael Shank | Riley | Mk XI | | Lexus | DP |
| 7 | Tuttle / Duno / Franchitti / Franchitti | SAMAX/Tuttle Team Racing (USA) | Peter Baron | Riley | Mk XI | | Pontiac | DP |
| 8 | Frisselle / Frisselle / Huisman | Synergy Racing (USA) | Cole Scrogham | Doran | JE4 | | Porsche | DP |
| 10 | Taylor / Collard / Angelelli / Briscoe | SunTrust Racing (USA) | Bill Riley | Riley | Mk XI | | Pontiac | DP |
| 12 | Fernandez / Haberfeld / Sharp | Lowe's Fernandez Racing | Tom Anderson | Riley | Mk XI | | Pontiac | DP |
| 13 | Pot / Boulle / Howard | Primus Racing | | Multimatic | MDP1 | | Ford | DP |
| 14 | Small / McGehee / Herring / Martin / Friedman | Autometrics Motorsports (USA) | Cory Friedman | Porsche | 996 GT3 Cup | | Porsche | GT |
| 16 | Dyson / Dyson / Gavin / Smith | Howard - Boss Motorsports (USA) | Maxwell Crawford | Crawford | DP03 | | Pontiac | DP |
| 17 | Arnold / Seyffarth / Mowlem / Shep | SAMAX (USA) | Peter Baron | Porsche | 997 GT3 Cup | | Porsche | GT |
| 19 | Gidley / McDowell / Baron | Finlay Motorsports | Steve Cameron | Crawford | DP03 | | Ford | DP |
| 21 | Van Uitert / Connolly / de Quesada / Sutherland / Sutherland | Matt Connolly Motorsports | Matt Connolly | BMW | M3 | E46 | BMW | GT |
| 22 | Assentato / Pumpelly / Longhi / Dumoulin | Fiorano Racing | Giovanni Panico | Porsche | 996 GT3 Cup | | Porsche | GT |
| 23 | Rockenfeller / Luhr / Long | Alex Job Racing/Emory Motorsports | Alex Job | Crawford | DP03 | | Porsche | DP |
| 24 | O'Shaughnessy / Cotter / Malloy / Shalit | Matt Connolly Motorsports (USA) | Matt Connolly | BMW | M3 | E46 | BMW | GT |
| 28 | Finlay / Valiante / Herta / Rice | Finlay Motorsports | Steve Cameron | Crawford | DP03 | | Ford | DP |
| 36 | Levitas / Pumpelly / Pobst / Baas | TPC Racing (USA) | Michael Levitas | Porsche | 996 GT3 Cup | | Porsche | GT |
| 39 | Cheever, Jr. / Fittipaldi / Carpentier | Cheever Racing | Eddie Cheever, Jr. | Crawford | DP03 | | Lexus | DP |
| 40 | Bingham / Ruhlman / Fellows | Derhaag Motorsports (USA) | Chris Bingham | Riley | Mk XI | | Pontiac | DP |
| 41 | Nonnamaker / Nonnamaker / Nonnamaker | Team Sahlen (USA) | Mike Thomas | Porsche | 996 GT3 Cup | I | Porsche | GT |
| 43 | Nonnamaker / Nonnamaker / Nonnamaker / Allen / Michaelian | Team Sahlen (USA) | Mike Thomas | Porsche | 996 GT3 Cup | | Porsche | GT |
| 46 | Baughman / Mason / Yeakle | Michael Baughman Racing (USA) | Michael Baughman | Chevrolet | Corvette | | Chevrolet | GT |
| 48 | Hauser / Dubler / Seiler / DeFontes | WTF Engineering | Gwen Petersen | Chevrolet | Corvette | | Chevrolet | GT |
| 50 | Zogaib / James / Nastasi / Gleason | Blackforest Motorsports | Brian Nott | Crawford | DP03 | | Ford | DP |
| 51 | Erdos / Newton / Hughes / Johansson | Cheever Racing | Eddie Cheever, Jr. | Crawford | DP03 | | Lexus | DP |
| 55 | Arnold / MacAlpine / Miller | ASC Motorsports | Zach Arnold | Chevrolet | Corvette | | Chevrolet | GT |
| 57 | Riggins / Rice / Stevenson | Stevenson Motorsports (USA) | John Stevenson | Chevrolet | Corvette | | Chevrolet | GT |
| 58 | Donohue / Law / Maassen / Christopher | Red Bull/Brumos Porsche (USA) | James Bailie | Fabcar | FDSC/03 | | Porsche | DP |
| 60 | Patterson / Negri / Allmendinger / Wilson | Michael Shank Racing | Michael Shank | Riley | Mk XI | | Lexus | DP |
| 64 | Edwards / Collins / Pilgrim / Magnussen | TRG (USA) | Kevin Buckler | Pontiac | GTO.R | | Pontiac | GT |
| 65 | Lally / Bunting / Valentine / O'Connell | TRG (USA) | Kevin Buckler | Pontiac | GTO.R | | Pontiac | GT |
| 66 | Johnson / Nearn / Sauvage / Ortelli | TRG (USA) | Kevin Buckler | Porsche | 997 GT3 Cup | | Porsche | GT |
| 67 | Bullock / Kroczek / Keith / Flanagan | TRG (USA) | Kevin Buckler | Porsche | 997 GT3 Cup | | Porsche | GT |
| 68 | Lowe / Greist / Pace | TRG (USA) | Kevin Buckler | Porsche | 996 GT3 Cup | | Porsche | GT |
| 69 | Vargo / Vargo / Refenning / Herrington | TRG (USA) | Kevin Buckler | Porsche | 996 GT3 Cup | | Porsche | GT |
| 70 | Tremblay / Haskell | SpeedSource | Sylvain Tremblay | Mazda | RX-8 | | Mazda | GT |
| 71 | Wilkins / Lacey / Wilkins / Martini | SAMAX/Doncaster Racing | John Lacey | Porsche | 997 GT3 Cup | | Porsche | GT |
| 73 | Tafel / Cawley / Price / *McQueen | Tafel Racing (USA) | Tony Dowe | Porsche | 996 GT3 Cup | | Porsche | GT |
| 74 | Lux / Espenlaub / Davis / Rahal | Tafel Racing (USA) | Tony Dowe | Porsche | 997 GT3 Cup | | Porsche | GT |
| 75 | Krohn / Jönsson / Bergmeister / Braun | Krohn Racing | Jeff Hazell | Riley | Mk XI | | Pontiac | DP |
| 77 | Brix / Barber / Borcheller / Jourdain | Feeds The Need/Doran Racing (USA) | Kevin Doran | Doran | JE4 | | Ford | DP |
| 78 | Zacharias / Brix / Barber / Jourdain | Doran Racing (USA) | Kevin Doran | Doran | JE4 | | Ford | DP |
| 80 | Murry / Keen | Synergy Racing | Cole Scrogham | Porsche | 996 GT3 Cup | | Porsche | GT |
| 81 | Marshall / Marshall / Prewitt / Pew | Synergy Racing (USA) | Cole Scrogham | Porsche | 996 GT3 Cup | | Porsche | GT |
| 82 | Werner / Peter / Quester / Wolff | Farnbacher Racing/Farnbacher Loles | Horst Farnbacher | Porsche | 997 GT3 Cup | | Porsche | GT |
| 83 | Farnbacher / Fitzgerald / Ehret / Basseng | Farnbacher Loles/Orbit Racing | Gregory Loles | Porsche | 997 GT3 Cup | | Porsche | GT |
| 84 | Robinson / Dallenbach, Jr. / Dallenbach / Brassfield | Robinson Racing | James Fraser | Riley | Mk XI | | Pontiac | DP |
| 86 | Kitch / Pennington / Gagne / Pallis | Synergy Racing (USA) | Cole Scrogham | Porsche | 997 GT3 Cup | | Porsche | GT |
| 87 | Gaylord / Hill / Hill / Diefenbach | Synergy Racing (USA) | Cole Scrogham | Porsche | 997 GT3 Cup | | Porsche | GT |
| 88 | Wagner / Wilton / Konstant / Poscente / Kapudija | Maverick Motorsports | Eric Burch | Chase | CCE-001 | | Pontiac | DP |
| 89 | Figge / Dalziel / Fogarty / Empringham | Pacific Coast Motorsports | Tyler Tadevic | Riley | Mk XI | | Pontiac | DP |
| 91 | Schramm / Baldwin | RVO Motorsports (USA) | Dave Watson | Fabcar | FDSC/03 | | Pontiac | DP |
| 92 | Stewart / Stewart / Gilbert / Stewart / Ave | TPC Racing (USA) | Michael Levitas | Porsche | 996 GT3 Cup | | Porsche | GT |
| 93 | Stewart / Stewart / Gilbert / Ave | TPC Racing (USA) | Michael Levitas | Porsche | 996 GT3 Cup | | Porsche | GT |
| 97 | Cummins / Ave | CyberSpeed Racing | Charles Long | Riley | Mk XI | | Pontiac | DP |
| 99 | Stallings / Gurney / Vasser / Moran, Jr. | Gainsco/Blackhawk Racing (USA) | Bob Stallings | Riley | Mk XI | | Pontiac | DP |