Andretti Autosport team-mates Alexander Rossi and Ryan Hunter-Reay swapped cars during the open test at Laguna Seca ahead of the final race of the 2019 season.
In the latter stages of the session, Rossi jumped into Hunter-Reay's #28 DHL car while Rossi's #27 NAPA car was run by Hunter-Reay.
The pair tried out each other's cars with the aim of helping to find a more optimum setup, in the hope of delivering a more consistent weekend for the Andretti squad, which could help Rossi in his battle for his maiden IndyCar title.
Rossi currently lies 41-points behind Team Penske's Josef Newgarden and could win the championship if his rival finishes outside the top five.
"Yeah, we've done that in the past, especially in testing," said Hunter-Reay. "With the open test, an extra day like this, it gave us the opportunity to come here with drastically different setups.
"What would take you maybe two and a half hours to change setups, that different. We had an opportunity where Alex and I like similar things in the car, similar setups, similar driving styles.
Hunter-Reay explained how his and Rossi's similar body shapes and weights allowed for the swap which benefited the team's setup direction for the weekend ahead.
"We're both the same height kind of, build. We can jump in each other's cars with very little modifications. We did it at the same time of day. It gives us a clear read as to the two setups, what we can then go forward with the rest of the weekend.
"Maybe some things from one car apply to qualifying and others to the race. It was definitely a beneficial exercise for us."
