The Dane was hired by Ed Carpenter Racing after impressing in a recent test at Barber Motorsports Park, and will make his IndyCar debut next season with a road and street course deal in addition to contesting the Indianapolis 500 in a third car.
Team owner Ed Carpenter will take over Rasmussen's regular #20 machine for the six oval races, while team regular Rinus VeeKay will return for a fifth season with the squad.
Unlike the previous two seasons, ECR has no plans to run a third car at events outside of the Indy 500.
This course has been chosen as the team seeks to maximise its resources after a disappointing 2023 that yielded just four top 10 finishes between Carpenter, VeeKay, Conor Daly and his mid-season replacement Ryan Hunter-Reay.
“A lot of it was just taking an assessment of where we were and how the year went, what went well and what didn't, how do we take a step forward,” Carpenter said.
“The series is so competitive now from top to bottom. For us, it was as much as anything about making sure we're using the resources that we have with all of our personnel and cars and preparation and putting our best foot forward.
“We staffed up more last year for the third car than we had in the past, but that's still probably less than what other two-car teams would average. As much as anything, we weren't happy with how we performed last year overall.
“Doing the same exact thing again wasn't going to be the ultimate fix. If we could have got enough additions into the team on all sides of things from engineering down through the mechanics, maybe we could have come to a different conclusion.
Source: Autosport