"Unfortunately, I'm not making any excuses, but we just need a bit more time and we'll be ok, but I'm disappointed with myself but it is what it is," McLaughlin said.
"It's very intimidating in regards to having a go in the Indycar, learning the space around you as well. I'm used to hitting mirrors off on the walls in Australia, not necessarily a tyre - but we're pushing out there trying to find the limits in a fast forward motion.... it's been an awesome initiation and we'll just come back and have another go tomorrow."
The 27-year-old decided to leave the Supercars arena in 2021 to take up a full-time driving position in next year's Indycar Series, driving for Team Penske and completing the team's four-car, full-season lineup.
McLaughlin leaves the Supercars arena ranked fourth on the all-time wins list with 56 career victories, and second on the all-time list with 76 career poles in just eight full seasons of racing.
McLaughlin will join former Indycar series champions Josef Newgarden, Will Power and Simon Pagenaud in Team Penske's 2021 Indycar lineup, with the 2021 season beginning in March.