| << 2018 | 2020 >> |

| # | pic | Versenyző | Nemz. | Autó | Csapat | Chassis/motor |
| 2 | Josef Newgarden | USA |
| Team Penske | Dallara IR18- Chevrolet | |
| 4 | Matheus Leist | Brazil |
| A.J. Foyt Enterprises | Dallara IR18- Chevrolet | |
| 5 | James Hinchcliffe | Kanada |
| Arrow Schmidt Peterson Motorsports | Dallara IR18- Chevrolet | |
| 7 | Marcus Ericcson (R) | Svéd |
| Arrow Schmidt Peterson Motorsports | Dallara IR18 - Honda | |
| 7 | Conor Daly | USA |
| Arrow Schmidt Peterson Motorsports | Dallara IR18 - Honda | |
| 9 | Scott Dixon | Új-Zéland |
| Chip Ganassi Racing | Dallara IR18 - Honda | |
| 10 | Felix Rosenqvist (R) | Svéd |
| Chip Ganassi Racing | Dallara IR18 - Honda | |
| 12 | Will Power | Ausztrál |
| Team Penske | Dallara IR18- Chevrolet | |
| 14 | Tony Kanaan | Kolumbia |
| A.J. Foyt Enterprises | Dallara IR18- Chevrolet | |
| 15 | Graham Rahal | USA |
| Rahal Letterman Lanigan Racing | Dallara IR18 - Honda | |
| 18 | Sebastien Bourdais | Francia |
| Dale Coyne Racing with Vasser-Sullivan | Dallara IR18 - Honda | |
| 19 | Santino Ferrucci (R) | USA |
| Dale Coyne Racing | Dallara IR18 - Honda | |
| 20 | Ed Jones | Dubai |
| Ed Carpenter Racing | Dallara IR18- Chevrolet | |
| 20 | Ed Carpenter | USA |
| Ed Carpenter Racing | Dallara IR18- Chevrolet | |
| 21 | Spencer Pigot | USA |
| Ed Carpenter Racing | Dallara IR18- Chevrolet | |
| 22 | Simon Pagenaud | Francia |
| Team Penske | Dallara IR18- Chevrolet | |
| 26 | Zach Veach | USA |
| Andretti Autosport | Dallara IR18 - Honda | |
| 27 | Alexander Rossi | USA |
| Andretti Autosport | Dallara IR18 - Honda | |
| 28 | Ryan Hunter-Reay | USA |
| Andretti Autosport | Dallara IR18 - Honda | |
| 30 | Takuma Sato | Japán |
| Rahal Letterman Lanigan Racing | Dallara IR18 - Honda | |
| 59 | Max Chilton | Angol |
| Carlin | Dallara IR18- Chevrolet | |
| 59 | Conor Daly | USA |
| Carlin | Dallara IR18- Chevrolet | |
| 88 | Colton Herta (R) | USA |
| Harding Steinbrenner Racing | Dallara IR18 - Honda | |
| 98 | Marco Andretti | USA |
| Andretti Herta Autosport w/ Marco & Curb-Agajanian | Dallara IR18 - Honda |
| # | pic | Versenyző | Nemz. | Autó | Csapat | Chassis/motor |
| 3 | Helio Castroneves | Brazil |
| Team Penske | Dallara IR18- Chevrolet | |
| 23 | Charlie Kimball | USA |
| Carlin | Dallara IR18- Chevrolet | |
| 24 | Sage Karam | USA |
| Dreyer & Reinbold Racing | Dallara IR18- Chevrolet | |
| 25 | Conor Daly | USA |
| Andretti Autosport | Dallara IR18 - Honda | |
| 31 | Patricio O'Ward (R) | Mexikó |
| Carlin | Dallara IR18- Chevrolet | |
| 31 | Sage Karam | USA |
| Carlin | Dallara IR18- Chevrolet | |
| 31 | RC Enerson | USA |
| Carlin | Dallara IR18- Chevrolet | |
| 32 | Kyle Kaiser (R) | USA |
| Juncos Racing | Dallara IR18- Chevrolet | |
| 33 | James Davison | Ausztrál |
| Dale Coyne with Byrd & Belardi | Dallara IR18 - Honda | |
39 |
Pippa Mann | Angol |
| Clauson-Marshall Racing | Dallara IR18- Chevrolet | |
| 42 | Jordan King | Angol |
| Rahal Letterman Lanigan Racing | Dallara IR18 - Honda | |
| 48 | J. R. Hildebrand | USA |
| Dreyer & Reinbold Racing | Dallara IR18- Chevrolet | |
60 |
Jack Harvey (R) | Angol |
| Meyer Shank Racing with Arrow SPM | Dallara IR18 - Honda | |
| 63 | Ed Jones | Dubai |
| Ed Carpenter Racing | Dallara IR18- Chevrolet | |
| 66 | Fernando Alonso (R) | Spanyol |
| McLaren Racing | Dallara IR18- Chevrolet | |
| 81 | Ben Hanley (R) | Angol |
| DragonSpeed | Dallara IR18- Chevrolet |