Renault's powertrain department in Viry took risks with last year's RE22 engine on the basis that it could gain performance before its specification was frozen, and then deal with reliability issues with FIA-approved fixes if necessary.
However, in 2023, it was clear that the essentially unchanged RE23 still lagged behind rivals Honda, Mercedes and Ferrari by around 20-30 bhp.
With the backing of the FIA, efforts were made this summer to gain support for an update programme that would have put Renault on a par with the other manufacturers for the last two years of the current regulations in 2024 and 2025.
However, that strategy was abandoned and in effect, Renault has accepted its deficit for the next two seasons and switched its full focus to developing a new engine for the 2026 regulations.
Asked if an engine deficit was frustrating for the chassis side of the team, Harman denied that was the case.
"I wouldn't say frustrating," he said. "I think we tried. I think it's important that we try these things. In the end, we have the technology and the capability to put the power unit where we'd like it to be, we just ran out of time on the RE22.
"We were very courageous with that engine. Okay, it's a little bit behind where we'd like it to be. But it used to be a long way behind, and we made a big step, but we just didn't quite get there enough.
"And we just couldn't take any more risks than we did, it would have been nice to have it unlocked for a little while just to do that again.
"But in the end, I think it's also important to note that we've got another power unit to do at the moment. That's a big focus for the team. And that's where we see our future.
"So I think we took a decision in the end, actually, to just focus on the future. And we'll deal with this power unit for the next two years by trying to remove some of its parasitic losses and do everything that we can do inside the regulations."
Harman conceded that the team didn't always do enough in 2023 to optimise the A523 for high-speed venues.
"You've all seen the numbers, we've stated the delta that we have," he said. "It's not just about the power unit deficit. If we look at Monza, and we look at how we performed there, it was not a good weekend for us.
"We didn't expect to be there. We knew the performance delta for the power unit before we went in, but we didn't expect to be in that position.
"And that tells you something that we just didn't do enough on the chassis side to complement the power unit and make the best of it. And that's something we actually learned for Las Vegas."
He added: "We do have to make some compromises, of course, you have to re-optimise your car into a different zone. I think there's a lot you can do. And I don't think we did enough at some of the circuits where the power unit dominates."
