| << 2019 | 2021 >> |

| # | pic | Versenyző | Nemz. | Autó | Csapat | Chassis/motor |
| 1 | Josef Newgarden | USA |
| Team Penske | Dallara IR18 - Chevrolet | |
| 4 | Charlie Kimball | USA |
| A.J. Foyt Enterprises | Dallara IR18 - Chevrolet | |
| 5 | Patricio O'Ward | Mexikó |
| Arrow McLaren SP | Dallara IR18 - Chevrolet | |
| 7 | Oliver Askew (R) | USA |
| Arrow McLaren SP | Dallara IR18 - Chevrolet | |
| 7 | Helio Castroneves | Brazil |
| Arrow McLaren SP | Dallara IR18 - Chevrolet | |
| 8 | Marcus Ericsson | Svéd |
| Chip Ganassi Racing | Dallara IR18 - Honda | |
| 9 | Scott Dixon | Új-Zéland |
| Chip Ganassi Racing | Dallara IR18 - Honda | |
| 10 | Felix Rosenqvist | Svéd |
| Chip Ganassi Racing | Dallara IR18 - Honda | |
| 12 | Will Power | Ausztrál |
| Team Penske | Dallara IR18 - Chevrolet | |
| 14 | Tony Kanaan | Brazil |
| A.J. Foyt Enterprises | Dallara IR18 - Chevrolet | |
| 14 | Dalton Kellett (R) | USA |
| A.J. Foyt Enterprises | Dallara IR18 - Chevrolet | |
| 14 | Sebatien Bourdais | Francia |
| A.J. Foyt Enterprises | Dallara IR18 - Chevrolet | |
| 15 | Graham Rahal | USA |
| Rahal Letterman Lanigan Racing | Dallara IR18 - Honda | |
| 18 | Santino Ferrucci | USA |
| Dale Coyne Racing with Vasser-Sullivan | Dallara IR18 - Honda | |
| 20 | Conor Daly | USA |
| Ed Carpenter Racing | Dallara IR18 - Chevrolet | |
| 20 | Ed Carpenter | USA |
| Ed Carpenter Racing | Dallara IR18 - Chevrolet | |
| 21 | Rinus VeeKay (R) | Holland |
| Ed Carpenter Racing | Dallara IR18 - Chevrolet | |
| 22 | Simon Pagenaud | Francia |
| Team Penske | Dallara IR18 - Chevrolet | |
| 26 | Zach Veach | USA |
| Andretti Autosport | Dallara IR18 - Honda | |
| 26 | James Hinchcliffe | Kanada |
| 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 | |
| 55 | Álex Palou (R) | Spanyol |
| Dale Coyne Racing with Team Goh | Dallara IR18 - Honda | |
| 59 | Max Chilton | Angol |
| Carlin Motorsports | Dallara IR18 - Chevrolet | |
| 59 | Conor Daly | USA |
| Carlin Motorsports | Dallara IR18 - Chevrolet | |
60 |
Jack Harvey | Angol |
| Meyer Shank Racing | Dallara IR18 - Honda | |
| 88 | Colton Herta | USA |
| Andretti Harding Steinbrenner Autosport | 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 | Scott McLaughlin (R) | Új-Zéland |
| Team Penske | Dallara IR18 - Chevrolet | |
| 3 | Helio Castroneves | Brazil |
| Team Penske | Dallara IR18 - Chevrolet | |
| 24 | Sage Karam | USA |
| Dreyer & Reinbold Racing | Dallara IR18 - Chevrolet | |
| 29 | James Hinchcliffe | Kanada |
| Andretti Autosport | Dallara IR18 - Honda | |
| 31 | Felipe Nasr (R) | Brazil |
| Carlin Motorsports | Dallara IR18 - Chevrolet | |
| 41 | Dalton Kellett (R) | USA |
| A.J. Foyt Enterprises | Dallara IR18 - Chevrolet | |
| 45 | Spencer Pigot | USA |
| Rahal Letterman Lanigan Racing w/ Citrone-Buhl Autosport | Dallara IR18 - Honda | |
| 47 | Conor Daly | USA |
| Ed Carpenter Racing | Dallara IR18 - Chevrolet | |
| 51 | James Davison | Ausztrál |
| Dale Coyne Racing with Rick Ware Racing and Byrd Belardi | Dallara IR18 - Honda | |
| 66 | Fernando Alonso (R) | Spanyol |
| Arrow McLaren SP | Dallara IR18 - Chevrolet | |
| 67 | J.R. Hildebrand | USA |
| Dreyer & Reinbold Racing | Dallara IR18 - Chevrolet | |
| 81 | Ben Hanley (R) | Angol |
| DragonSpeed | Dallara IR18 - Chevrolet |