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.
“The competition just isn't on track, it's off track as well. Very hard to get new people into the building and away from other teams.
“This is a solution that allows us to be more focused and hopefully come back stronger in 2024, which is the plan.”
Carpenter said he had been impressed by Rasmussen's “natural ability and speed” in the Barber test and revealed that the 23-year-old's contract is not strictly set for only 2024.
“There's options for it to be multiple years,” Carpenter said.
“That's the intent, that this is more than a one-year project. I think if you look at our history, in most cases we've tried to build on relationships and grow them.
“I don't think it would be fair to say we're going to see Christian's full potential after one year. It's a jump.
“I expect him to be strong, but we want to be able to capitalise on his talent for the long run. That's our intent.”
When asked by Autosport if it would be possible for Rasmussen to run other oval events with another team to gain experience with a full-time schedule, similar to when Daly split time with ECR and Carlin in 2019 and 2020, Carpenter expressed a hesitancy toward the idea.
“Yeah, we haven't really talked about that,” Carpenter said.
“I'd say it's unlikely that we would be comfortable having him run with another team.
“I would say it's early enough that there's always potential to add to the programme that we have if the situation presents itself over time and we're able to do that.
“Certainly, the long-term goal is to have him running a full-time schedule, so we'll see how that develops. Right now, this is the plan.”
