| 00 | van der Merwe / Duxbury / Martin | Kreepy Krauly Racing (ZA) | Sarel van der Merwe | March | 83G | | Porsche | GTP |
| 01 | Hulse / Lott / Kennedy / DeFontes | THR Foreign Car (USA) | George Hulse | Porsche | 911 Carrera | RSR | Porsche | GTO |
| 02 | Gelles / Brummer / Cohen / *Helton | OMR Engines (USA) | Hoyt Overbagh | Chevrolet | Camaro | | Chevrolet | GTO |
| 03 | Adams / Mason / Thompson | Mason Racing | Kim Mason | Chevrolet | Monza | | Chevrolet | GTP |
| 04 | Adam / Bedard / Redman | Group 44 (USA) | | Jaguar | XJR-5 | | Jaguar | GTP |
| 05 | Morejon / Garcia / Almeida | Hi-Tech Racing (USA) | Bill McDill | Porsche | 935 | M16 | Porsche | GTP |
| 07 | Heimrath / Heimrath, Jr. | Heimrath Racing (CDN) | Ludwig Heimrath | Porsche | 930 | | Porsche | GTP |
| 09 | Tisdelle / Van Every | Van Every Racing (USA) | | Porsche | 911 Carrera | RSR | Porsche | GTO |
| 1 | Andretti / Andretti | Dr. Ing. H. C. F. Porsche (D) | | Porsche | 962 | | Porsche | GTP |
| 2 | Leon / Leon / Wolters | Leon Bros Racing (USA) | Leon Brothers | March | 84G | | Chevrolet | GTP |
| 3 | Madren / Pickering / Speer | Pegasus Racing (USA) | | March | 84G | | Buick | GTP |
| 4 | Hagan / Labonte / Felton | Stratagraph/Piedmont (USA) | Billy Hagan | Chevrolet | Camaro | III | Chevrolet | GTO |
| 5 | Akin / O'Steen / Rahal | Bob Akin Motor Racing (USA) | Bob Akin | Porsche | 935 | -84 | Porsche | GTP |
| 6 | Foyt / Wollek / Bell / *Henn | Henn's Swap Shop Racing (USA) | Preston Henn | Porsche | 935 | L | Porsche | GTP |
| 6A | | B.F. Goodrich (USA) | Jim Busby | Lola | T616 | | Mazda | GTP |
| 7 | Pridgen / Bond / Tilton | E. J. Pruitt & Sons | | Porsche | 911 | | Porsche | GTU |
| 8 | Lewis / Beasley / Ashford | Rennsport Enterprise (USA) | | Porsche | 911 Carrera | RSR | Porsche | GTO |
| 9 | Baker / Mullen / Blackaller | La Jolla Trading Group (USA) | Wayne Baker | Porsche | 935 | K3 | Porsche | GTP |
| 10 | Kendall / Johnson / White | Dave White Racing | | Porsche | 924 | Carrera GTR | Porsche | GTU |
| 11 | Ruttman / Laws / Schoenfeld / Richmond | Dillon Enterprises | Ray Dillon | Chevrolet | Camaro | | Chevrolet | GTP |
| 13 | Rubino / *Rodriguez / *Vitolo | Rubino Racing (USA) | | Mazda | RX-7 | | Mazda | GTU |
| 15 | Kalagian / *Lloyd / *Mills | Kalagian Ardisana (USA) | John Kalagian | Lola | T600 | | Chevrolet | GTP |
| 16 | Lanier / Hinze / Whittington | Marty Hinze Racing (USA) | | March | 83G | | Chevrolet | GTP |
| 17 | Bacon / Krueger / Guest | Al Bacon Racing (USA) | Al Bacon | Mazda | RX-7 | | Mazda | GTU |
| 18 | "Fomfor" / Naon / Montoya / *Valiente | Fomfor Racing (ES) | "Fomfor" | Sauber | C7 | | BMW | GTP |
| 19 | Miller / Ramirez / Smith | Performance Motorcar (USA) | Jack Miller | Nimrod | NRA/C2 | | Aston Martin | GTP |
| 20 | Canary / Sanborn / Gonzalez | Paul Canary Racing (USA) | | Chevrolet | Corvette | | Chevrolet | GTO |
| 21 | Field / Newsum / McFarlin | Oftedahl Racing (USA) | Gordon Oftedahl | Pontiac | Firebird | | Pontiac | GTO |
| 22 | Schwarz / Allen / Spenard | Oftedahl Racing (USA) | | Pontiac | Firebird | | Pontiac | GTO |
| 23 | Carney / *Davenport / *Hindson | New Raytown Datsun (USA) | Frank Carney | Datsun | 200SX | | Datsun | GTU |
| 24 | Hefner / Griffin / Gralia | Pegasus Racing (USA) | Martin L. Speer | Porsche | 935 | JLP-2 | Porsche | GTP |
| 25 | Cowart / Miller / DeNarvaez | Red Lobster Racing (USA) | David Cowart | March | 82G | | Porsche | GTP |
| 25T | Cowart / Miller / DeNarvaez | Red Lobster Racing (USA) | David Cowart | March | 83G | | Chevrolet | GTP |
| 26 | Nehl / Hansen / Silcox | Zabatt | | Chevrolet | Corvette | | Chevrolet | GTO |
| 27 | Fowells / Potter / Mummery | Scuderia Rosso (USA) | Jim Fowells | Mazda | RX-7 | | Mazda | GTU |
| 28 | Mallock / Olson / Sheldon | Ray Mallock Racing (GB) | | Nimrod | NRA/C2 | B | Aston Martin | GTP |
| 29 | Cooper / Evans / Smith | CAM Motorsports (GB) | | Nimrod | NRA/C2 | | Aston Martin | GTP |
| 32 | Price / Alderman / Baird | Lee Industries/Alderman Datsun (USA) | George Alderman | Datsun | 280ZX | | Datsun | GTU |
| 33 | Keck / Wessel / Chastain | K & P Racing (USA) | Karl Keck | Chevrolet | Corvette | C3 | Chevrolet | GTO |
| 35 | Smith-Haas / Gilgan / Zouzelka / *Griffin | Team Dallas (USA) | George Drolsom | Porsche | 911 Carrera | RSR | Porsche | GTO |
| 37 | Burdsall / Northam / Welter | Vero Racing Ent. | | Mazda | RX-7 | | Mazda | GTU |
| 38 | Mandeville / Johnson / Smith | Mandeville Auto/Tech (USA) | Roger Mandeville | Mazda | RX-7 | | Mazda | GTO |
| 39 | Newsome / Diehl / Kreider / Sereix | Luger Reality (USA) | Dale Kreider | Chevrolet | Corvette | C3 | Chevrolet | GTO |
| 40 | Bieri / Pallavicini / Gysler | Bieri Racing (CDN) | | BMW | M1 | | BMW | GTO |
| 41 | Schmidt / Schmidt / Schmidt | Starved Rock Lodge | | Chevrolet | Corvette | | Chevrolet | GTO |
| 42 | Boone / Long / Bontempi | Ken Moore (USA) | Ken Moore | Porsche | 911 | | Porsche | GTU |
| 43 | Davey / Montoya / Goellnicht | Walker-Brown Racing (USA) | | BMW | M1 | | BMW | GTO |
| 44 | Bundy / Hobbs / Tullius | Group 44 (USA) | | Jaguar | XJR-5 | | Jaguar | GTP |
| 45 | Morton / Lobenberg / Garcia | Conte Racing (USA) | Phil Conte | Lola | T600 | | Chevrolet | GTP |
| 46 | Fassler / Jellinek / Molnar | Tycos Racing (USA) | | Pontiac | Firebird | | Pontiac | GTO |
| 47 | Bohren / Dingman / Bighouse | Dingman Bros Racing (USA) | Dingman Brothers | Chevrolet | Corvette | C3 | Chevrolet | GTO |
| 49 | Bender / Boand / Utt / Currin | Comp. Fiberglass | Bard Boand | Chevrolet | Corvette | | Chevrolet | GTO |
| 51 | Wilder / DeFranceschi / McCall | Chris Wilder | Chris Wilder | Porsche | 911 | S | Porsche | GTU |
| 53 | Overby / Bell / Pelz / *Kleinschmidt | Daytona Racing (USA) | | Pontiac | Firebird | | Pontiac | GTO |
| 54 | Redding / Long / Copeman / Jolly | Bob Copeman (USA) | Bob Copeman | Porsche | 911 Carrera | RSR | Porsche | GTO |
| 55 | Stevens / Brainard / Herman | Preston & Son Ent. | | Mazda | RX-7 | | Mazda | GTU |
| 57 | Febles / Ferrer | Diego Febles Racing (PR) | Diego Febles | Porsche | 911 Carrera | RSR | Porsche | GTO |
| 58 | Trueman / Gregg / Mena | El Salvador Racing (ES) | | Porsche | 924 | Carrera GTR | Porsche | GTU |
| 60 | Cook / Morrison / Swan | Team Morrison | | Mazda | RX-7 | | Mazda | GTU |
| 61 | O'Neill / Courtney / Sereix | Deco Sales Associates (USA) | | Chevrolet | Monza | | Chevrolet | GTO |
| 63 | Downing / Maffucci / Ganz | RGP 500 Racing (USA) | | Argo | JM16 | | Mazda | GTP |
| 66 | Dunham / Lewis / Kline | Mike Meyer Racing (USA) | Mike Meyer | Mazda | RX-7 | | Mazda | GTU |
| 67 | Busby / Knoop / Hayje | B.F. Goodrich (USA) | Jim Busby | Lola | T616 | | Mazda | GTP |
| 68 | Halsmer / Grable / Knoop / Quester | B.F. Goodrich (USA) | Jim Busby | Lola | T616 | | Mazda | GTP |
| 69 | Hofstra / Shafer / Uria | John Hofstra | | Porsche | 911 | | Porsche | GTU |
| 70 | Weitzenhof / Loring / Honegger | Z & W Motorsports (USA) | | Mazda | GTP | | Mazda | GTP |
| 72 | Riggins / Delano / Petery | Centurian Auto Transport (USA) | | Chevrolet | Camaro | III | Chevrolet | GTO |
| 73 | Howey / Crabtree / Wolf | Howey Farms (USA) | Clark Howey | Chevrolet | Camaro | II | Chevrolet | GTO |
| 75 | Young / Varde / Gregg | Bob Gregg Racing (USA) | Bob Gregg | Chevrolet | Camaro | | Chevrolet | GTO |
| 76 | Young / Reed / Baldwin / Cook | Malibu Grand Prix (USA) | | Mazda | RX-7 | | Mazda | GTU |
| 77 | Baker / Marlin | Southern Racing Promins | John Josey | Chevrolet | Corvette | | Chevrolet | GTO |
| 79 | Bergstrom / Ireland / Winters | Whitehall/Promotion (USA) | | Porsche | 924 | Carrera GTR | Porsche | GTU |
| 81 | Saucier / Franklin / Gravel | Diamond Racing | | Datsun | Z | | Datsun | GTU |
| 82 | Mueller / Casey / Visger | Firestone (USA) | Casey/Haggard | Mazda | RX-7 | | Mazda | GTU |
| 83 | Gassaway / Pfeifer / Tayar | Diamond Racing | Michael Gassaway | Chevrolet | Camaro | | Chevrolet | GTO |
| 84 | Young / *Grunnet / *Burt | Auto-Line Motorsport (USA) | Clay Young | Pontiac | Fiero | | Pontiac | GTU |
| 85 | Fonseca / Fallas / "Jamsal" | Latino Racing (CR) | | Porsche | 911 Carrera | RSR | Porsche | GTO |
| 86 | Holbert / Ballot-Léna / Haywood / Leven / *Nierop | Bayside Disposal Racing (USA) | Bruce Leven | Porsche | 935 | /80 | Porsche | GTP |
| 87 | Forbes-Robinson / Schneider / Williams | Performance Motorsports (USA) | | Porsche | 924 | Carrera GTR | Porsche | GTU |
| 88 | Murray / Valentine / Barnett | Motorsport Marketing | Ken Murray | Chevrolet | Camaro | | Chevrolet | GTO |
| 90 | Schaefer / Andretti / Nicholson / Refenning | 901 Shop (USA) | | Porsche | 911 | SC | Porsche | GTU |
| 91 | Taylor / Figaro / *Novella | Walter Johnston | | Pontiac | Firebird | | Pontiac | GTO |
| 92 | Attwood / Elford / Meister / Hagestad | Brumos Racing (D) | | Porsche | 928 | S | Porsche | GTO |
| 93 | Marsh / Marsh / Pawley | Mid-O Racing (USA) | | Mazda | RX-7 | | Mazda | GTU |
| 94 | Gardner / Sanders / Durovy | Tangent Racing | | Pontiac | Firebird | | Pontiac | GTO |
| 97 | Shelton / Shelton / *Ballot-Léna | Tide & Mosler Racing | Warren Mosler | Ferrari | 512 BB | /LM | Ferrari | GTP |
| 98 | Dallenbach, Jr. / Chandler / Aase | All American Racers (USA) | Dan Gurney | Toyota | Celica | Mk III | Toyota | GTU |
| 99 | Cord / Adams | All American Racers (USA) | Dan Gurney | Toyota | Celica | Mk III | Toyota | GTU |