| 00 | Carpenter / Scheckter / George / Foyt | Vision Racing | Larry Curry | Crawford | DP03 | | Porsche | DP |
| 01 | Scott Pruett | TELMEX Chip Ganassi with Felix Sabates (USA) | Mike Hull | Riley | Mk XI | | Lexus | DP |
| 02 | Dixon / Wheldon | Target Chip Ganassi with Felix Sabates (USA) | Mike Hull | Riley | Mk XI | | Lexus | DP |
| 05 | Auberlen / Alhadeff / Sigal / Wendlinger | Sigalsport BMW | Emmanuel Lupe | Riley | Mk XI | | BMW | DP |
| 06 | Reese / Pilgrim / Edwards / Collins | Banner Racing (USA) | Leighton Reese | Pontiac | GXP.R | | Pontiac | GT |
| 07 | Edwards / Pilgrim / O'Connell / Collins | Banner Racing | Leighton Reese | Pontiac | GXP.R | | Pontiac | GT |
| 08 | Goldin / Goldin / Finger | Goldin Brothers Racing | Steve Goldin | Mazda | RX-8 | | Mazda | GT |
| 3 | Lewis / Ruhlman | Southard Motorsports | Steve Southard | Riley | Mk XI | | Lexus | DP |
| 6 | Zogaib / James / Tracy / Allmendinger | Michael Shank Racing | Michael Shank | Riley | Mk XI | | Lexus | DP |
| 7 | Kimber-Smith / Enge / Bucknum | SAMAX | Peter Baron | Riley | Mk XI | | Pontiac | DP |
| 10 | Taylor / Angelelli / Gordon / Magnussen | SunTrust Racing | Debbie Savini | Riley | Mk XI | | Pontiac | DP |
| 11 | Duno / Manning / Carpentier / Dalziel | SAMAX | Peter Baron | Riley | Mk XI | | Pontiac | DP |
| 12 | Schramm / Baldwin / Lester | RVO Motorsports | Dave Watson | Riley | Mk XI | | Pontiac | DP |
| 14 | Patch / McGehee / Allen / Hamblin / Friedman | Autometrics Motorsports | Cory Friedman | Porsche | 997 GT3 Cup | | Porsche | GT |
| 15 | Nastasi / Tagliani / Cosmo / Gigliotti | Blackforest Motorsports | Brian Nott | Ford | Mustang Cobra | GT | Ford | GT |
| 16 | Dyson / Dyson / Smith / Gavin | Howard Motorsports (USA) | Richard Howard | Crawford | DP03 | | Pontiac | DP |
| 17 | Lacey / Wilkins / Arnold / Mowlem / Papadopoulos | Doncaster Racing | John Lacey | Porsche | 997 GT3 Cup | | Porsche | GT |
| 18 | Alzen / Renauer / Borcheller / Mazzacane / Pastorelli | VICI Racing | Ron Meixner | Fabcar | FDSC/03 | | Porsche | DP |
| 19 | Finlay / Valiante / McDowell / Labonte | Finlay Motorsports | Steve Cameron | Crawford | DP03 | | Ford | DP |
| 20 | Wallace / Leitzinger / Stewart | Howard Motorsports | Richard Howard | Crawford | DP03 | | Pontiac | DP |
| 21 | Alessi / Connolly / Kapudija | Matt Connolly Motorsports | Matt Connolly | BMW | M3 | E46 | BMW | GT |
| 22 | de Quesada / Dumoulin / Gabel | Alegra Motorsports/Fiorano Racing | Carlos de Quesada | Porsche | 997 GT3 Cup | | Porsche | GT |
| 23 | Bergmeister / Dumas / Long | Alex Job Racing | Alex Job | Crawford | DP03 | | Porsche | DP |
| 24 | Dennard / Pickett / Cotter | Matt Connolly Motorsports (USA) | Matt Connolly | BMW | M3 | E46 | BMW | GT |
| 27 | | O'Connell Racing | Kevin O'Connell | Porsche | 996 GT3 Cup | | Porsche | GT |
| 28 | McQuiston / Feinberg / Safina | At Speed Motorsports | Bob Miller, Sr. | Porsche | 997 GT3 Cup | | Porsche | GT |
| 29 | | Extreme Motorsports Group | Anthony Puleo | Nissan | 350Z | | Nissan | GT |
| 39 | Fittipaldi / Cheever, Jr. / Collard / Maassen | Cheever Racing | Eddie Cheever, Jr. | Crawford | DP03 | | Porsche | DP |
| 41 | Brent / Michaelian / Michaelian / Malloy / Becker | Team Sahlen (USA) | Mike Thomas | Porsche | 996 GT3 Cup | I | Porsche | GT |
| 42 | Mayes / Kaemmer / Auriemma / Willcox | Team Sahlen | Mike Thomas | Porsche | 996 GT3 Cup | | Porsche | GT |
| 43 | Sahlen / Nonnamaker / Nonnamaker / Nonnamaker | Team Sahlen | Mike Thomas | Chevrolet | Corvette | | Chevrolet | GT |
| 46 | Baughman / Collyer / Connolly | Michael Baughman Racing (USA) | Michael Baughman | Chevrolet | Corvette | | Chevrolet | GT |
| 47 | Morgan / Morgan / Bernhard / Zacharias | TruSpeed Motorsports | Rob Morgan | Riley | Mk XI | | Porsche | DP |
| 48 | Hauser / Dubler / Magner / DeFontes | WTF Engineering | Gwen Petersen | Chevrolet | Corvette | | Chevrolet | GT |
| 49 | Sahlen / Nonnamaker / Nonnamaker / Nonnamaker | Team Sahlen | Mike Thomas | Pontiac | GTO | | Pontiac | GT |
| 51 | Newton / Erdos / Brix | Cheever Racing | Eddie Cheever, Jr. | Fabcar | FDSC/03 | | Porsche | DP |
| 52 | | Mastercar (I) | Mario Crugnola | Ferrari | 360 Modena | Challenge | Ferrari | GT |
| 57 | Cicero / Bunting / Gue / Stevenson | Stevenson Motorsports (USA) | John Stevenson | Chevrolet | Corvette | Z06 | Chevrolet | GT |
| 58 | Donohue / Law / Rice / Sharp | Red Bull/Brumos Porsche | Michael Colucci | Riley | Mk XI | | Porsche | DP |
| 59 | France / Haywood / Barbosa / Moreno | Brumos Porsche/Kendall (USA) | Michael Colucci | Riley | Mk XI | | Porsche | DP |
| 60 | Patterson / Negri / Castroneves / Hornish, Jr. | Michael Shank Racing | Michael Shank | Riley | Mk XI | | Lexus | DP |
| 61 | Wilkins / Empringham / Frisselle / Frisselle | AIM Autosport | Ian Willis | Riley | Mk XI | | Lexus | DP |
| 63 | Spencer / Spencer / Grupp | Team Spencer Motorsports | Reece Harper | Mazda | RX-8 | | Mazda | GT |
| 64 | Lowe / Pace / Van Overbeek / Kelleners | TRG (USA) | Kevin Buckler | Porsche | 997 GT3 Cup | | Porsche | GT |
| 65 | Gomez / Marden / Milner / Peterson | TRG (USA) | Kevin Buckler | Porsche | 997 GT3 Cup | | Porsche | GT |
| 66 | Lally / Pumpelly / Valentine / Greenberg / Buckler | TRG (USA) | Kevin Buckler | Porsche | 997 GT3 Cup | | Porsche | GT |
| 67 | Bourque / Cloet / Solley / Harris | TRG (USA) | Kevin Buckler | Porsche | 997 GT3 Cup | | Porsche | GT |
| 68 | Ballou / Jaeger / Gleason / DeSimone II | TRG (USA) | Kevin Buckler | Porsche | 997 GT3 Cup | | Porsche | GT |
| 69 | Assentato / Longhi / Segal | SpeedSource | Sylvain Tremblay | Mazda | RX-8 | | Mazda | GT |
| 70 | Haskell / Tremblay / Ham / Pobst | SpeedSource | Sylvain Tremblay | Mazda | RX-8 | | Mazda | GT |
| 72 | Davis / Swartzbaugh / Liddell / Tafel | Tafel Racing | Tony Dowe | Porsche | 997 GT3 Cup | | Porsche | GT |
| 73 | Nielsen / Martini / Quester / Peter | Tafel Racing | Tony Dowe | Porsche | 997 GT3 Cup | | Porsche | GT |
| 74 | Lux / Henzler / Farnbacher / Tafel | Tafel Racing | Tony Dowe | Porsche | 997 GT3 Cup | | Porsche | GT |
| 75 | Krohn / Jönsson | Krohn Racing | Jeff Hazell | Riley | Mk XI | | Pontiac | DP |
| 76 | Braun / Papis / Lehto | Krohn Racing | Jeff Hazell | Riley | Mk XI | | Pontiac | DP |
| 77 | Gollin / Gidley / Jourdain / Servia | Doran Racing | Kevin Doran | Doran | JE4 | | Ford | DP |
| 81 | Johnson / Westbrook / Lietz / Huisman | Synergy Racing | Cole Scrogham | Porsche | 997 GT3 Cup | | Porsche | GT |
| 82 | Kitch / Pennington / Pallis / Bawcutt | Synergy Racing | Cole Scrogham | Porsche | 997 GT3 Cup | | Porsche | GT |
| 83 | Gaylord / Pickering / Hilton / McCrackin | Synergy Racing | Cole Scrogham | Porsche | 997 GT3 Cup | | Porsche | GT |
| 84 | Robinson / Dallenbach, Jr. / Dallenbach / Legge | Robinson Racing | James Fraser | Riley | Mk XI | | Pontiac | DP |
| 85 | Keen / Ehret / Werner / Hardt | Farnbacher Loles Motorsports | Alan Lourenco | Porsche | 997 GT3 Cup | | Porsche | GT |
| 86 | Bowman / Bell / Willsley / Price | Farnbacher Loles Motorsports | Gregory Loles | Porsche | 997 GT3 Cup | | Porsche | GT |
| 87 | Zugel / Burke / Jeannette / Eversley | Farnbacher Loles Motorsports | Gregory Loles | Porsche | 997 GT3 Cup | | Porsche | GT |
| 88 | Loles / Miller / Pank / Plumb / Stanton | Farnbacher Loles Motorsports | Gregory Loles | Porsche | 997 GT3 Cup | | Porsche | GT |
| 89 | Ellis / Grande / Rossi / Wellon / Friedman | Autometrics Motorsports | | Porsche | 997 GT3 Cup | | Porsche | GT |
| 91 | Matthews / Goossens / Johnson / Hunter-Reay | Lowe's Riley-Matthews Motorsports | Bill Riley | Riley | Mk XI | | Pontiac | DP |
| 97 | | Stevenson Motorsports | John Stevenson | Chevrolet | Corvette | Z06 | Chevrolet | GT |
| 99 | Gurney / Fogarty / Stallings / Vasser | Gainsco/Bob Stallings Racing | Bob Stallings | Riley | Mk XI | | Pontiac | DP |